6.4/8hp70 project 67 Barracuda

That may not make 800+ but I would put a Ford 9" in there instead. Tons of parts readily available, both used/ junk and aftermarket, it's stronger than an 8 3/4, and looks enough like one that most guys won't give it a second thought. And, if you want to swap gears here and there, it's a "short job"