If you haven't already seen it and used it, Currie has a great online calculator for determining your rear end,
9+ Rearend Calculator - Overall Width.
We built one a few years ago for a now gone project. Bought the pumpkin from Randy's Ring & Pinion for like $125, 3" DOM tubing and Torino style bearing ends from Art Morrison for another $125, then borrowed a friends alignment tool to set it all up with.
$250 and a couple hours and we had a rear end. Pretty cool.
