Factory A/C Into Non-A/C Cab??

[69sixpackbee]

I am tired of screwing with the aftermarket, sub-standard "all-in-one" A/C & heater units. Suffice it to say thay suck. They cool great but the total recirculating systems have their drawbacks. I have all of the components down to the last screw to put the factory Four Season system into my '72. Is ther much that I need to do to the firewall openings to make this install work. I believe that the two cutouts are different sizes from the standard cab and the A/C cab besides having the heater core access holes drilled through the firewall as well. I am going to use the underdash vents I currently have so I am not going to fuss with the balls or the upper center vent. I am either going to use my existing Sanden SD5H14 compressor with the re-adjusted POA to keep with the 134A (I dont want to put on the A6) or I will adapt a V5/V7 compressor and can the POA.
I have a few options both of which are very feasable. My only concern is the cutouts in the firewall.
Has anyone here done this type of swap into a non-A/C cab?
Thanx and Happy Holidays!!
Bud Weaver