No real lateral support at the legs on that seat.
I have sparco Evo2 in mine, but had to do some trimming of the seats to fit. Look through my build thread on Rx7club for photos of install. Let me know if you need a solid mount that bolts to the floor, I can make you one just like mine, head maximum clearance.
http://www.rx7club.com/showthread.php?t=525920&page=35