I am a big person and am 6 "6 and i was wonder what type of sports cars i could fit in ti?
A lot of it depends on where your height is - legs or torso.
My best friend is 6'8, and I'm 6'2, but I have super-short legs and my torso is longer than his! Because of this, he actually fits better in my S2000 than I do! (that said neither of us fit in it well at all, I just bought it cause it's the best car ever). My legs fit the S2000 just fine - I don't have to have the seat back all the way even - but the top of my head is actually higher than the windshield, so I had to buy a lowered seat bracket for the front.
The Mustang is a better bet than the 370z, most likely. That said you'd best go and sit in them to see which will work better.