I did the Vintage Air Sere-fit kit on the '69 Coronet R/T (440 non-A/C car.) It cools, but I don't care for the semi-hidden lines that run under the fender.
I would rather have the firewall bulkhead and lines run inside the engine compartment.
No problem with the replacement electronic slider switch/controls. Not sure about the retro-fit kit that uses the factory control panel?
On my '69 Coronet 500 (318 factory air), I want to keep the factory heater/Evaporator (flushed/cleaned) box under the dash.
I might try using the factory condenser (flushed/cleaned) and expansion valve with the 134A freon?
I have a new Sanden SD-508 134A compressor, a new dryer with Binary switch, and I will make new hoses/lines (bought the Mastercool 71550 manual A/C Hose Crimper tool when I did the R/T.)
I believe the recovery of the old R12 freon, and charging the system with the new 134A, needs to be done by someone with an EPA 608/609 certification?