Blocker - if you're planning on putting a V8 in that project car, you would be better off to start with a V8 car. There are a lot of differences between the V8 cars and the I6 other than the motor. Check out Stef Robert's site for the parts she is swapping to go from I6 to V8. Of course if your planning on a complete resto mod with new suspension, steering, transmission and rearend, then forget the above advice.
http://home.pacifier.com/~dnstoys/mustang.htm