A true Mach1 or a fast back Stang?

[442w30]

Not quite.

The fastback was one of 3 available bodystyles for the Mustang. They marketed it as the SportsRoof.

The Mach I was only available as a SportsRoof.

The GT was available on any bodystyle. There is no "standard" bodystyle.

All engines save the Boss engines were available on all bodystyles. Smart people ordered the 428CJ in the coupe, but they probably only made around 50 of them. Non-Mach I fastbacks with the CJ are also extremely rare, and if you're gonna encroach into Ford territory, I'd suggest checking out these sleepers.