I suggest the following: Buy on the basis of body condition and price. Since you intend to replace the driveline anyway, don't make a 5.0 a necessity. Just stay away from any inline six models as those necessitate a K member replacement for a V8 swap. Try to get a trunk model as they are stiffer and lighter; model years 79-83 would put you at 25 years old and would mean no emissions tests. If you don't have your heart set on a Chevy engine, a much cheaper 351 with a $1,000. forged-piston stroker kit will net you a 408 and easy 11 second timeslips, 10's with a more race oriented application -NA of course (a stock crank 351 will easily put you in the 11's too). If you buy a non 5.0 or a 79-85 model, you will not get a posi 8.8 (12 bolt to you) rearend, but you can scrounge a rearend from an 87 or 88 Turbo T bird that bolts-in for $65. from Pull a Part. It will come with 3.55's or 3.73 gears. You have many aftermarket options too. If you want to go fast for the least, hard to beat a fox body. Hope that helps a little.
The heavier 94-95 5.0 models use a fox chasis, but the transmission input shaft and intake manifolds and rearends do not interchange with earlier fox chasis models. I would recommend not buying that model (called an SN95 to Mustang folks), because you are giving up a lot of interchangeability.
Last edited by esoteric; Apr 7, 2007 at 08:59 AM.