GPU upgrades for Aurora R5

I bought recently an Aurora R5, but maybe I chose a too limited GPU: GTX 960 with 2GB DDR5.

I've been perusing Amazon for other cards to upgrade in a near future. maybe a GTX 1060 or 1070 without SLI, single card. But I see many with fancy shapes and plenty of fans. [*-)]

Should any card fit in the Aurora R5? The only info I've been able to find is on page 16 of the setup manual, where it says that the maximum length is 10.5". But it says nothing about width or height.

PSU should not be a problem: I got the 850W one.

Is there an "official" source of upgrade parts?

Sorry. I come from Mac, and everything in the PC world is new to me.