Might want to have a look at what I did in the Sliger SM580 a couple years ago. Seems similar to your goals. If I didn’t already have a working system, I’d probably switch to that EK pump/block/res combo.
Highly suggest going 2x 280mm rads. My system is dead silent with it’s rad setup with a 6900XT and a 3900x.
Of course, that’s a significantly lower power CPU, but the silence just means there’s cooling headroom.
As for temps; under full synthetic load:
GPU: 65c
CPU: 72c
water: 40c
ambient: 21c
fans: 650rpm
pump: 2300RPM target