unless you were planning an extra tiny mATX build you shouldn't have much issue with size.
as long as the case fits a motherboard that has two or more available PCIe slots, than the case would be fine height-wise.
length from front to back can be a factor, but your average decent case will list it's dimensions.
just compare this to the length size listed in the GPU's spec details.
also be sure the case doesn't have drive bays or other junk in the way towards the front.
for your motherboard you may need to check the slot size of the cards; 2.5 slot, 3 slot, etc.
just to be sure the motherboard you're using has enough space between it's PCIe x16 slots to fit both cards.
a shopping list of nicer mid-large ATX cases, most with better cooling options and nicer looking:
NewEgg Case Wishlist.
my current two choices are the
be quiet! Silent Base 802 & the
Fractal Design Vector RS.
where are you planning on getting the cards?
there isn't much, if any, available stock anywhere and may not be for quite some time.