Hi all, I registered just for this post!
I wouldn't count the Spitfire out as a good IT car. I doubt you could make the power of a lot of other cars(ok maybe all) but the handling can be great as well as the brakes. The stock brakes with race pads, braided lines, and race fluid are plenty.
A baffled oil pan is all that is needed to fix any oiling problems. The 1500's main problem is keeping them together due to a long stroke, therefore, I recommend the 1296 engine which also gives reduced minimum weight.
I'm not saying this would be easy...but I think one could be set up well for ITC. I think the main disadvantage would be power.