Narrow rear end or use something else??

[Lowair]

Starting a build on a '69 swb i have had awhile. I want to run a 20X9.5 Wheel in the rear with a 3.5" OR 4" backspace. i have seen trucks that have done this by narrowing the stock rear end. My question is, has anyone achieved the desired effet by using a whole different rear end? IE, out of an S10, Camaro or the like. Seems it would be easier and cheaper to do that than cut and weld rear end housing, buy new axles, etc. Any help or ideas would be greatly apprciated. The guy that built this truck said he narrowed his rearend. Sadly, I recently found out he had passed away, didnt get to ask him the specifics of the narrowing. Awesome truck though.