I have a 1979 f150 I'd like to convert to A/C. I have a 73-79 A/C cab out in my back 40 and I'd like to somehow set up my truck for A/C. my question is, would I be better off just swapping dashes and all the components or just changing cabs completely? And what all would swapping dashes and AC components involve? What all would I have to find to make the AC work?

 

That sounds like a loaded question somewhat.
mechanical parts are easy to change, dash, vents, ducts.
But the actual hole in the cab is a huge problem, you'd have to replicate the same hole in the non-AC cab that is in the AC cab. I have no idea what that hole looks like, if it is ribbed/reinforced/odd shaped. I have not done this conversion and finding a crew cab that had factory AC is hard, I always assumed that I'd be cutting the portion of the firewall out of a factory AC cab and swapping it into mine.

But if your AC cab is in good shape, or you are willing to repair whats wrong with it, and it is the same color as the rest of your truck or you had planned on repainting anyhow, I'd say swapping cabs will probably be easier.

Be prepared for some to say that upgrading to a decent aftermarket will be less work, more efficient (sanden vs york) and will be all new compared to repairing the original and upgrading to R134.