Truthfully, going to places where street rods are gathered and finding what you like and want to replicate is the road to happiness in this area. Another is to pore through the magazines and read through their captions, hoping that they give actual sidewall info, which is usually there because it's such a key to the "look" of the car. In addition to selecting the "rubber rake" that you want, pick the tire OD that best fills the rear wheel arch for your eye, then look for the right wheel to sidewall ratio. One of the guys posted this link some time back, and I've looked at it several times but just because you see a tire size listed doesn't mean it's still made and on the market - Tire Sizes