>>299155626
I've got a GTX 980 and the Index with full body. 
Games runs usually pretty fine without any issue. 
If you pass by a mirror however it usually hiccups for a few seconds before smoothing out. 
Also best not to be in any room with 30+ people. 
Once in a while the game will run like ass but restarting the game itself seems to fix that. 

Honestly I think you'll be fine. The 980 isn't THAT much better than the 970 and Quest is running at a lower resolution than the index.

I've got a few other VR games as well so let me know if you want a performance rundown on any.
(Assuming you have a decent CPU since some of these are not that optimized)