Hey Jeff. I always liked Triumphs and had thought about the GT6 (almost bought one until the wife nixed it for space reasons. Damn her rational brain!!), but the 83 inch wheelbase scares me. I dont think I could FIT in the car. The Miata is tiny to me and its 89 inches. There is a good amount of info on how to set one up for racing tho.
I think the trick to running an oddball might be to find a car that has had some racing success in other countries and see if you can apply those lessons learned to cars brought stateside (i.e. lots of info on racing Saabs in Sweeden, Alfas in Italy, and Toyotas in Austrailia and Japan).
I also thought about the Omni/Charger as an ITB car. Where can you even get racing parts? That seems like it would be a big challenge.