Just to add what others have already reported, I am 6' 2", 215-220pounds, and slightly longer than average legs (36" inseam) and here are my findings:
AE86 Corolla with sunroof and stock seats-OK without helmet, helmet on just brushes roof. AE86 without sunroof, OK for me, even with helmet, but probably not to the tune of an extra 4" of headroom. AW11 MR2 is a very similar situation, fine for me with helmet, stock seats, but not really any extra headroom. Aftermarket seats might buy enough room in either car, but it would be a custom extra-low mount for sure. My rally car had aftermarket seats pretty much on the floor and I had probably 6" of headroom without helmet, no sunroof, and no headliner. The SW20 second-gen MR2 is fairly cavernous inside stock and well worth a try for you.
Supras and RWD Celicas seem fine to me when I've tried them, but I am not as familiar with them so I can't give accurately give too many details.