If I had my druthers, I'd be Kern Dog instead of myself. I'd be younger, better looking, and smarter. Alas, none of that is likely to happen. However, I'm the one contemplating this move. KD is just faster on the post - I got tied up taking undercoating off the Dart and never came up for air.
My 69 Dart is an A/C car, but there is nothing there. No compressor, brackets, cooler, lines, or anything else except the vents under the dash and those will be coming out. It doesn't get ugly hot here but about ten days a year so I have no intention going the A/C route. My problem is the heater box is badly broken, with the passenger fresh air door and big hunks of surrounding material broken out. It is not repairable so I was sniffing about for another one. We were looking at what he has and what I need, but it's apparent there are a lot of difference between A/C and non-A/C boxes and mounting. My core does not leak so I think I could get by with just a new box if I could find one. A local guy to me has a non-A/C box but it's clear it won't fit and I have no appetite for going down your road adjusting the firewall. Besides, I can't weld for crap.
My plan at this point is find an A/C box in good condition and put it in but block off the A/C items so they are non-op. The only other question is if I can graft on non-A/C controls which I would prefer. A/C has lots of vacuum lines and whatnot, non-A/C is manually cable controlled which I would prefer.
By the time I get done with this car, documentation for where all the cobbled-together parts came from will look like a desk dictionary.