Cab swap question

[sleepertruck72]

I am looking at cabs to swap the little window out of my 67 stepper. I looked at a pretty nice cab today from a 71 non AC auto with low tunnel. He also has a 69 (he thinks) A/C cab auto low tunnel cab that has more obvious repair needed (rockers, some windshield area rust, drip rail, roof dents) I want to eventually add a vintage air A/C system and I am wondering how much work it is to add the system into the non A/C cabs. I know I can drill the holes for the a/c balls and the one above the radio, but other than that I have no idea what else would be involved. If anyone here has done this swap, please let me know how much trouble it is or if I should just look for an A/C cab. I just hope the cab is as solid as it looks, the last cab I had looked great, and it was a can of worms