For you guys with a 68-72 Cutlass/442 with AC,and want to convert it to non-AC,I have all of the pieces to do it.My parts came from 70-72 Cutlass/442's,but most could also be used on 68/69,or I can get the pieces for those as well. I have non-AC firewall section,with the inner/outer heater boxes,all the ductwork,non-AC kickpanels,dash controls,and the cylinderical inserts for the upper corners of the dash,for the vents. $200.00 for a complete kit.
You will need to cut & weld the section into your existing firewell because the openings for the heater are in a different location.I have all of this.

Note: The post coupes did not have the cylindrical vent tubes in the upper corners,& had ventless dashes.They also had single-pull kickpanels.I have this type of stuff too.