While I love the Miata, you being taller then me I'd say C5. If you can find one in decent shape, adding a few well chosen bolt-ons like headers/exhaust, and shocks/springs and sway bars will get you past the C5Z. This will likely be my next car in years to come, LS power with great handling just can't be beaten for me. The drawback is that Corvette specific parts tend to have the Corvette tax added, but the savvy car guy can do well with take off parts from better models like the C5 or C6 Z06 as just about everything interchanges just like Miatas.
Well the C5 started in 97 and shares most of its chassis with the 2013 C6, while there are obvious differences in the lighter weight C6 Z06/ZR1 (mostly material use in construction of the chassis). The cars design makes the parts very interchangeable. The shocks, springs, sway bars, brakes, ect will all swap. Find some rich guy putting all kinds of shit on his C6 Z06 and you'll be the one profiting.
Otherwise just reading your thread title I was thinking Miata or S2000, and having drivin both I really think they do great. The Miata is about crap without some more power like a turbo or something. Obviously you don't fit in these well, and that would prevent me. Race seats are great, but I don't like riding in them all the time and for me the car needs to be enjoyable on and off the track.