Bignut

Hello all, I'm bored working from home so I've decided to take on overclocking my i7 6700k.
I'm learning it's less scary and complicated than I originally thought, which makes me regret not applying a light overclock when I bought my parts ~3 years ago.
 
Here are my relevant specs and what I'm at right now. Also please tell me if something looks off, I'm new to overclocking.
 
CPU: i7 6700k @ 4.6 ghz, 1.355v (Didn't mess with it a lot, pretty sure I can go slightly lower)
Cooler: Noctua NH-U9S (I have 2 fans on this in a push-pull config but I don't think it makes a difference)
RAM: Team T-Force DARK PRO 16 GB (2 x 8 GB) DDR4-3200 (using the xmp profile, 3200 mhz, 1.4v; Didn't push the timings)
Mobo: Gigabyte GA-Z170X-Gaming 7
Case: HAF XB EVO
 
At 4.6 ghz, my cpu idles at about 35-40C, under load it tops at ~75C. (I think that's typical?)
I got it stable 4.7 ghz @ 1.375v, but it started getting up to 85C and I decided that was out of my comfort zone.
To test stability I'm running Prime95's torture test for 5 minutes. If it doesn't crash after I call it good and so far I haven't had any problems.
 
Is purchasing a Cryorig R1 Ultimate or a Noctua D15 cooler a good option if I want to get the most out of overclocking my current CPU with the possibility of re-using said cooler when I upgrade? (No idea when I'll upgrade but hopefully not this year.) Also I prefer air coolers, no AIO water shenanigans. Is 1.4V for a CPU OC the "safe limit"? I haven't seen a consensus.  
Thanks!