If a 295 will fit most cars, then a 265 or 275, with a 9.5" wheel should fit, but obviously the backspace is critical. I think about 1/2" from the leaf spring is as close as I want to come. That leaves a little wiggle room when the car is under stress.
Newstalgia is a good looking supplier, but I'm a little disappointed in their tires. Seems they dont carry all the sizes, and not a huge selection. At least not on the website anyways. No selection of a 275/50 tire anywhere!? Maybe I'll just call them.