bam, at you pull it you can find 5.0s all day long in lincolns and mercs. same motor as the stang, jsut different heads, cam, intake.
if your gonan do a head cam intake anyway, you can get the block for like $60
find a t5 pretty easy to come buy and in the rang eof $100-$300
get a good clutch, and quadrant assembly.
youll need a flywheel as well.
here is a basic parts list
5.0 block
heads
cam
intake
carb
starter
flywheel
clutch kit (includes, throw out bearing, pressure plate, disc)
clutch cable
t5 trans
pilot bearing
clutch fork
dont knwo what kind of pump youll need, are you gonna do a cell or use oe tank on the rx7? fuel lines unles syou can use the stock ones, i dunno what all you can use form the 7. but those are a good list t ostart wiht for the stang parts.