Yes, any 9" pumpkin will fit a 9" housing, if you plan on cutting the tubes to narrow the rear end you should REALLY have a pro shop do it. Everything has to be aligned properly and welded properly. You can look on ebay, there are quite a few reputable sellers on there with a long history of positive feedback.
I bought my housing from Currie with the billet Torino bearing ends and 31 spline axels for $800 and bought a completely rebuilt 4 pinion 31 spline posi from a vendor on ebay for $500 shipped. This stuff isn't cheap so if you're really hurtin for $$$ then look for a wrecked hipo Mustang or other type Ford with a posi 9" in it.