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You should be able to use any ATX power supply.
The only thing you would have to be concerned about with old computers is they power the processor with 5v instead of 12v like modern computers do. Your motherboard has a 4 pin CPU power connector which gives 12v to the motherboard, so this is not a concern.
Older motherboards without that connector use 5v from the 20-24 pin connector to power the processor, and that can be a problem with modern power supplies because modern power supplies don't output a lot of watts on 5v and 3.3v (because most power hungry devices in modern computers, like cpu and video card, take power from 12v and convert it down to the voltages they need).
 
Avoid the absolute cheapest power supply models, and get something with good reviews, it doesn't have to be something fancy, as your old computer worked just fine with a 300 watts power supply.
 
If you're in US, the cheapest I would be comfortable recommending is these :
 
SeaSonic SS-400ET Bronze 400W ATX12V V2.2/EPS12V 2.91 SLI Ready CrossFire Ready 80 PLUS BRONZE Certified Active PFC Power Supply
EVGA 400 W ATX Power Supply (100-N1-0400-L1) - PCPartPicker
Thermaltake Smart Series 430W Continuous Power ATX 12V V2.3 80 PLUS Certified 5 Year Warranty Active PFC Power Supply Haswell Ready PS-SPD-0430NPCWUS-W
hec HEC-450TC-3WX 450W Power Supply - Newegg.com
 

There is nothing objectively wrong with your list, and if you had gone ahead and bought it, you would be very happy, no doubt.
I think it is a good idea that you are going to revisit your list, IMO, your motherboard/RAM selections were not on point.
 
Everything else is great.
My suggestion:
PCPartPicker Part List Type Item Price CPU Intel Core i5-10600K 4.1 GHz 6-Core Processor $299.99 @ Newegg CPU Cooler Noctua NH-U12S chromax.black 55 CFM CPU Cooler $69.98 @ Amazon Motherboard Gigabyte Z490 VISION G ATX LGA1200 Motherboard $199.99 @ Amazon Memory Crucial Ballistix 16 GB (2 x 8 GB) DDR4-3600 CL16 Memory $92.99 @ Amazon Storage Samsung 970 Evo 500 GB M.2-2280 NVME Solid State Drive $99.99 @ Amazon Storage ADATA XPG SX8200 Pro 1 TB M.2-2280 NVME Solid State Drive $149.99 @ Adorama Video Card Asus GeForce RTX 2080 SUPER 8 GB STRIX GAMING Advanced Video Card $784.99 @ Best Buy Case Fractal Design Meshify C ATX Mid Tower Case $104.98 @ Newegg Power Supply be quiet! Straight Power 11 750 W 80+ Platinum Certified Fully Modular ATX Power Supply $149.90 @ Amazon   Prices include shipping, taxes, rebates, and discounts     Total $1952.80   Generated by PCPartPicker 2020-06-27 16:07 EDT-0400   Relax, it's not life and death.
C
 
Well...it is video game life and death isn't it. lol

Hey man, super excited for you. That's a nice chunk of $ to be working with.
Good build too, they really are your friends!
 
Questions:
What resolution to you plan on getting 144fps @? Do you already have a monitor? Which one?
Do you know/want to overclock your rig or would you like more of a turn key experience?
 
IMO stuff:
Intel platform make sense for your use case. In reference to my question above, the 106000010600K is a fun/great chip to overclock with. The 3600 is a more of a set  it and forget it type.
Get the Super. The Ti is...an historical piece
I dislike the timings of your RAM selection. Put an extra $40-50 bucks in to get some true CL16s, none of this 16-19 shit. Remember to check your motherboards QVL list.
 
GL.
Chris

And remember, always take photos through the glass or acrylic.

Do me a favor, push the two pin power connector on your GPU in just a weeee bit.
Thanks.
Chris

I bought my computer in 2012 and I decided that I finally needed some more grunt to power my gaming and app development. I am on a tight budget though so I couldn't justify buying new. I have watched every season of Scrapyard Wars and enjoyed them thoroughly, so I decided to finally have a go buying second hand.
 
I started with:
16GB DDR3 @2133Mhz
i5-4670K 4c/4t @3.40Ghz to 3.80Ghz
GTX 760 x 2
Asus Maximus VI Hero
 
I decided I was going to try and keep the motherboard, but to upgrade to a faster cpu with the same socket, preferably one with hyper threading. I needed more graphical grunt, in a single card, because many programs don't support SLI. I would also LOVE some more ram capacity (Chrome and VM's are thirsty).
 
I ended up buying:
32GB DDR3 @1600
i7-4770 4c/8t @3.40Ghz to 3.90Ghz
RX 580
G19 Keyboard
G403 Wired/Wireless Mouse
 
Along the way I actually bought a GTX 960 first at a good price, then decided I wanted a bit more so that I could run VR comfortably. I also dumpster dived and found a working Q8200 DDR2 system with no hard drives which I parted out as well. Selling my original components, the intermediate graphics card and the dumpster pc I broke even. I haven't noticed the decrease in my ram and the extra capacity goes a long way. The hyperthreading means I am no longer getting bottlenecked in my programming and VM's. The GPU lets me play almost any game at full detail at 1080/60 as well as most VR games. Overall I've noticed a HUGE improvement (Fire Strike score 9350 to 11500) and it only cost me some off peak public transport fees. A+ would recommend.

PS: This all happened around Christmas, I wasn't helping to spread Covid.

I found two useful resources for finding the best B550 boards from Gigabyte Aorus and Asus. Hopefully this can help you guys decide what to get.
 
 
Asus :https://www.asus.com/microsite/motherboard/AMD-B550/doc/ASUS_B550_Full_Specs.pdf
Gigabyte Aorus: https://docs.google.com/spreadsheets/d/1l5iWx3_UbFTkvMJy9Du4PVH_fiOR5BpZ3R64lbwky7U/edit?usp=sharing
 

WD Toshiba and Seagate are the only HDD makers out there.
 
WD was the only one to brand DM-SMR drives for NAS use though. DM-SMR drives work mostly ok in desktops.
 
There really aren't any alternatives, go ssds, or just buy CMR drvies.

Again, you need to explain in a bit more detail what you plan on using the machine for.
However, a few quick observations:
GPU seems weak No need for the Hyper 212 Memory timing are not very good on that kit (16-20-20-38) I would advise you push the budget for a 24" monitor. GL with your build!

Using the 3,5mm out will likely disable the integrated speakers and some TVs don't have a menu option to re-enable it so the soundbar sounds like a must.
When you go wireless with the headphones you risk getting a slight delay in them. Might not be a problem for a hearing-impared but just so you know. It sounds like an echo in the sound if you can hear the sound from the soundbar and the headphones.
To reduce the delay, i'd skip the bluetooth. It's just one extra conversion which can only add to the delay. Although, I guess with a quality device it can still be unnoticeable.
I myself have no experience of iAnything. Always trusted Logitech in all my peripherals. 

I'd advise doing a fresh Windows 7 Install on the new board, then upgrade to Windows 10. Transferring windows across chipsets can cause issues with conflicting drivers and such, so clean install is the way to go. 

Take with a grain of salt.  B) 
 
32GB of RAM is excessive, 16GB is fine for gaming+.
2TB will fill up pretty fast, and you don't have any redundancies("backups"). So you'll need moar storage space.
I have two 840 pros in raid and its worth it!
Whats an Optical drive? <-- No need. Get a digital copy of windows.
If you like the Corsair AIOs the get the H100i instead*.
GL!
 
*Note Check for compatibility first but iirc its fine