I would imagine you could get an 8" rim under the rear of one of those cars pretty easily.

The best way I know to figure out what fits short of copying somebody else is to first measure what's on the car now. Find out how much clearance you have to the leaf springs, fender lip, upper control arm etc. Once you have the existing numbers you can take the backspacing and tire size of the ones your are considering and add or subtract against your existing setup and you should be able to figure it out.