Stock 1987 IROC, ride height and all. Will wheels and tires off a 2007 Corvette base model 2LT fit my car without making any modifications? Here is the tire sizes. 245 40 ZR18 with +56 offset and 285 35 ZR19 with +79 offset.

Yes, but you will need 2-2.5 inch spacers front & rear. Plus the fender gap might be bigger then you think with the lower side wall tires. Plenty of pics of c6 rims on 3rd gens, do a search and see if they are right for you.