Anon helping his astronomy telescope program boomer neighbor here. Here are the two parts lists I've come up with (many thanks to anons in the previous thread for helping with this)
Intel build:
https://pcpartpicker.com/list/gYbPTM
AMD build:
https://pcpartpicker.com/list/gjqZ74
I've gone ahead and sent these to him; but I have to give a final input on which one to go with. Previously, some of you said that AMD's IMC is shit and struggles with large amounts of RAM. For cost and complexity's sake, I settled on 2x64GB as frankly the idea of 4X64GB scares me on a deep level. I was aiming for a budget around $4,000; still waiting on a response from him as to whether he's willing to go full nuclear threadripper mayhem and drop $20k on a build. Knowing him, I would assume not.
For those who missed the previous thread, this is the program which he's using for astrophotography
https://pixinsight.com/benchmark/
https://pixinsight.com/sysreq/index.html
The GPU would just need to drive a couple of big 4K monitors. Most important is the CPU and RAM, second most important is storage speed, which I believe both those NVME SSDs handle easily. I think the builds are 95% finalized.