If you’re looking for an “overkill” system and you don’t need it for a couple of weeks, you might consider the new Samsung 960 M.2 drive - it’s screamingly fast compared to pretty much everything else out there. They’re not going to be out for a few weeks, though.
I just built a “pseudo-overkill” system, but only with a single 1070 card. It’s effectively the same as the gaming system you link to, but with a better motherboard (the Gaming 7 from Gigabyte), the single 1070, and only 16 gigs of RAM. I only overclocked it a little (to 4.4 GHz), so I used an aircooled system instead of liquid for the CPU. It gets a solid 90 Hz on everything I’ve thrown at it so far, and was only about $1800. For the difference in price, you could buy two of my setup… and a whole extra VR rig.
If it’s for a development system, I’d suggest something more like the Cooler Master HAF XB II EVO instead of that gamer box. It’s much, much easier to get into and work on for a research environment.