You can use any ASA you want - the grip comes with standard mounting points (nuts retained within the grip, so you're threading into metal, not the plastic of the frame), so you can either bolt on a direct mount or attach a rail to take a rail mount. Only thing to be aware of is that the nuts which hold the ASA in place are mounted fairly deep, so stock bolts for something like a CP Direct mount might not be long enough.
I had an old Dye Airport and rail going spare and fitted that to mine:
