Air conditioner for my 65 dart slant 6.

Both of you should search for the thread on exactly this question. It has many photos, some from me. Briefly, yes there are aftermarket brackets for modern Sanden compressors, but sketchy drawings, never saw a photo, and not sure if readily available. We do know they are pricey. Best factory solution is the ~1978 Aspen/Volare brackets for a Sanden, especially if you also want power steering. There is always the factory RV2 compressor, which was used thru the 1980's. It is reliable, but a very heavy beast.