280mm radiator on nzxt s340 case enough for cpu and gpu?

[MaiaTuga_03]

So I wanted to build a custom water cooling loop for my cpu and gpu in my NZXT S340 case but I had a few questions about the radiator and fans.
First my pc specifications:
 

• motherboard x470 gaming plus
• CPU ryzen 5 2600 six core OC to 3.9 ghz(maybe a bit higher with water cooling)
• GPU RX 590 Sapphire nitro + ddr5 8 gb (hoping to overclock it's frequency with water cooling)
• 2 NZXT case fans
• RAM Ripjaws 16gb(2x8) 3200mhz

So I know the case supports a 280mm or 240mm radiator at the front, a 120mm at the top and another 120mm at the back. So my questions were:

• Do I have to buy 3 radiators(a 280mm and two 120mm) or can i just buy a 280mm radiator and compensate with radiator height, and if so, how tall should my radiator be to cool my cpu and gpu?
• Can I place the radiator(s) with the fans facing the inside of the case?(I'm buying RGB fans so I wanted them to be visible from the front panel).

Note that i am overclocking both the cpu and gpu.