www.tirerack.com has good tire sizing info on their site. Pick any tire you like and click on the 'specs' tab for the tire. It will give what rim widths will fit for the tire and what the tire is sized for.

Also, for that body with 9" in the rear, be careful to have the right backspacing on those rims.

I'm shopping for 9.5" rears for my '72 RR now, and based on leaf spring clearance, and fender clearance, about 5.5" BS should work about right.
For 9" rims, 5 to 5.5" BS would work pretty good, I imagine.

For tires, 245 to 275 section width would probably fit.