NVMe drive for storage instead of SSD. It will be about 6 times faster from around 500MB/sec to 3GB/sec.
AMD black could be any number of CPUs. They're all slow compared to newer AMD CPUs though.
6 HD screens...maybe he would consider upgrading to larger 4K monitors instead. Each 4K monitor has the same resolution as 4 HD monitors. So 2x40 inch monitors has more screen estate than 6 HD monitors. And two or even three 4K monitors could be run from the same graphics card.
So that is would I would look into. Newest AMD CPU, 1 really good graphics card, NVMe for storage and new larger monitors.