66 Valiant ~ Wheel size / offset question

I fall in the category of I don't know what I don't know. Ideally a 15" wheel, but I don't know what I can fit or what is recommended.
Possibilities are limitless. Is it going to be a "hot rod" or more of a stock, low-budget car? Do you want to be able to rotate the tires? Do you want to modify the wheelwells and/or fenders in order to fit the fattest/biggest tires you can on it? What's the budget? "Mags" or steel wheels?