it just comes down to backspacing and overall width of the rim. If you go wider, go with more backspacing too which will keep the tires tucked under the truck like you want. The only potential issue is rubbing the inner wheelwell. You can get a pretty wide tire on a 10" rim though. How wide a tire are you thinking of?
i'm getting near needing new tires for my 83 C1500 pick-up, and I'm thinking of 255/70's on the factory ralley's. That's a 10" section width, roughly 8.75" of tread surface and a little over 29" tall. Basically a little taller and wider than the 235/75's that are on it now.
Rene