Help finding the correct wheel size

[kneeless]

Time to spend the load on rims and tires. I have a 70 Camaro with a stock 12 bolt rear end, with wilwood brakes on the rear. Up front i have tubular upper and lower control arms, stock spinndles and wilwood brakes. I also have Qa1's all the way arround. There are no alterations to the body at all. I'd like to put 20's on the rear and 18's or 19's on the front. Please give me your thoughts. THK's