In a 90, you may be able to pull it off? The depth is pretty good, you just won't have the same length. I say do it. Even a 75, whatever, just give it a go if you want to downsize. You'll know if they aren't happy. 3.5 inches for a purple is not large by any means and the Kole I wouldn't think will grow much more....Thanks! The kole is about 4.5 inches and the Purple 3.5in.