Yes they should fit both your video cards. I have one on my 7800gt and another one coming. On my Asus A8N-sli premium there is about a 2in space between the cards, which are plenty of room to accommodate both maze 4 gpu coolers. Besides the maze 4 is only about 1/4 in higher than the stock cooler once installed anyways.
Went home and measured it. THe two blocks on the two 7800 should barely clear it by 1/8 of an inch. Phew.