Converting a chevy non A/C cab to a factory A/C type

[70Chevy4x4Nut]

I have a 1970 4x4 chevy Pickup with a factory A/C cab. It is rusted on the top lip of the windshield and has worked it's way to the inside. I worry about always having to repair this type of rust (not super bad but not sure how bad it is in the pillars that might start again later). I have an opportunity to get a better cab that is rust free but is non A/C. Can I install my dash and all components to make it a factory A/C type? Are there any major holes that need to be made through the firewall? Has anyone ever done that? And what would be the hardest part? I plan on doing a major restore so I will be gutting this truck anyway. Any information would be appreciated.

(This question not related to A/C swapout but I have to consider it since I'm swapping cabs.
Would I have to do anything about the hump area? I have the tall hump (with a cover) and this one may have the shorter hump. Did they come with a cover where it would be an easy swap or would the hump need to be cut out?

Thanks