Here's a few thing worth noting:
* Faster RAM speeds help Photoshop as seen here:
http://www.xbitlabs.com/articles/memory/display/haswell-ddr3_6.html
So, DDR3 2933Mhz vs 1600Mhz is better.
* For the price point, the Core I7 4770K is a very strong performer in 3d rendering... but it depends on the 3d program; if the 3d program he uses works VERY well with mulitiple cores, maybe a 6 core CPU might turn out better.
http://www.anandtech.com/bench/CPU/2
(check out the 3d rendering benchmarks)
Also, a Xeon might turn out well too:
http://anandtech.com/show/7852/intel-xeon-e52697-v2-and-xeon-e52687w-v2-review-12-and-8-cores/3
* As for the video card... well I guess it depends on the 3d program.
> What type of video card acceleration does he need in the modelling stage ... will it have a significantly large number of polygons, so much so, that maybe even one video card is not enough?
> What program(s) does he use to render with? Some render programs are faster on Nvidia, some on AMD, some render programs might not even use the video card.