And now for the rest of the story.
Pin drives are cool. After all, that's what the originals had. Drawback is...tire availability. If you go with 15" pin drives you've got about 3 tires to choose from and none of them are particularly good when compared to the choices that you have in 16, 17, and 18's. If you're just a cruiser, and tires (grip) is not a big issue, go 15's. A big block and big HP with 15" wheels and Goodrich T/A's seem like a contradiction to me, IMHO.
I think I read or heard that someone is making 17" rims for the pin drive setup. Now THAT would be cool. TONS of GOOD tire choices and pin drive. Doesn't get much better.