When are you too large for an early A body....

I'm 6'3 185# with a long spine.

I do not physically fit in a miata, a z3 or a Viper.

However, I did fit just fine in a vintage mg and a vintage triumph.

The older sports cars had much deeper foot wells. A friend of mine who was about your size when I met him back in 1977 had an MG Midget. It was a trick to get in and out, but once in he fit.