[Jeff Lee]

You can run a 304 or 360 2bbl or a 360 or 390 4bbl. Uses a GM A-body style 4-link.
You can run a t-flite 904 0r 727 style trans (t-flite with AMC bolt pattern) or even a T-400 or BW auto.
Garrett Monde ran one up until this year and is now building a '70 AMX for D/S to get into a faster class. There are pictures of his Rebel "The Machine" on Class Racer. It worked well and was not a money pit.
From what the ad says and pictures indicate, $6500 looks like a good price. Probably top dollar as there is not much of a following but what else can you find that is supposedly rust free and complete for that kind of money?
If a Road Runner / Fairlane or Impalla is your style, this one is almost as appealing.