Tires, 335 or 345 Michelin pilot

[snappytravis]

I am wondering on tire sizes. I have 18x10 fronts and 19x12 rears. Car is 69 Camaro with art Morrison chassis and dse tubs. I am thinking of 245/35/18 on the front and 325 or 345/30 19s for the rear. I have right at 14 inches to the qtr lip, I believe the Michelin pilot is 13.8 on a 11.5 wheel. How is this measurement going to change on a 12 wide wheel if any? It's almost on the ground,,, finally.
Thanks Travis