AC in 67 barracuda

Vintage Air kits and knee knocker units that hang under the dash are all designed for those vehicles that aren't built for/with factory air. While the compressor, belt/pulley setup, etc.., is variable with engine choice,, What goes inside a factory a/c car isn't so variable. If you really would rather first have a non a/c setup inside so you can add air to it, altering or replacing a section of the factory firewall would be required.
Since you are talking rally dash and willing to modify that bezel, 100 percent of factory air from a 73,4, A-body would be my target. Why? The pre 73 push button climate controller is a trouble maker, their chromed pot metal vent assembly is prone to pitting and breaking, etc.., etc...
The very sweetest homemade retrofit is single DIN stereo head unit placed where the factory climate controller was. Climate controller goes where "fecked up" factory radio windows were. I wouldn't trade mine for anything else I've seen.