Would change the keyboard for a full size, as he does not want 10 keyless. That mouse is expensive but sounds like a chinese knock off on Amazon. The speakers also seem like that, and he already has some.
According to this page on UserBenchmark.com, they suggest the 5950X over the 11400. Where are you pulling this data from, saying that they recommend Intel over AMD?
Originally he wanted 2 3090s in SLI but then I told him about the 6900XT with the slightly but cheaper cost and just like 10% performance loss. It has less market share but it makes up in the textures and such*
* = according to UserBenchMark.com
he has a 200" desk and 49" * 3 is 147" he could fit a 4th monitor but that is another $800
edit:
conversions:
200" = 508cm
49" = 124.46cm
147" = 373.38cm