Nice brakes.
First time I have seen Pro Race 1.2s on a yank. Had them on an Xsara VTS track car a few years back, really great for unsprung weight. I'd imagine you would notice the weight of more OEM wheels on the steering (probably to a lesser extent the vette magnesium rims).
As far as I am concerned both wheels should fit, I had 17" vette wheels before my American Racings and before that 18" BMW wheels and they fit fine.
Either way you'll get a decent price for the TDs in that fitment, the BMW track lads would snap them up at a guess.