72 vs 73 heater boxes

I've got a 73 Dart Sport, AC car. The harness is chewed up in the engine bay and the under the dash. I also want to get rid of the underdash AC stuff.

I've got a 72 Duster parts car. I'm going to bring over the engine bay and underdash wiring harness. I also want to bring over the 72 heaterbox and dash controls.

Question: anyone have any insight of possible problems? I assume the heater box will bolt up properly....what do you think?