Slant 6 727 Transmission

That could be possible. I do know that slants with 727's were available for taxi and "fleet" use. I do, however question a 8 3/4 in a 1970 "A" body. Some body correct me if I'm wrong. In 1970 it either had small bolt pattern drum brakes or big bolt pattern disc brakes. I don't think the 8 3/4 "A" rear was available in 1970, and if it was, those rears were small bolt pattern. A 8 3/4 with big bolt pattern would have been too wide for the "A" body. If the car was ordered as "trailer towing", I think the LBP disc brakes would have been standard/mandatory
EDIT: I did some parts book checking. What I posted about the rear above is incorrect. 70-71 still had small bolt pattern KH disc brakes ( not the BBP single piston caliper). Also the 8 3/4 rear is listed in the parts book for the Valiant/Dart bodies. So as MMissile posed, that is a viable combination.