Automotive Air Conditioning Information Forum

I am trying to prepare ahead to do this conversion. I have a 502 BBC crate motor which came with an R4 compressor. The car is a 34 Ford replica build that I have been working on and has less than 900 miles on it. Basically it has a Vintage Air system with a dryer. This is the second R4 on the car already and its starting to leak oil so I am looking to replace it. Vintage air has a mount kit, but says it only works on small block chevy. Im sure I can get a mount kit to work, after all the bolt pattern is going to be the same to mount a Sanden 508 into any R4 mount. After mounting I would like to know what else would need to be done. The R4 uses Pag 100 oil, what does the Sanden use. This system has less than 100 miles on it, does it need to be completely flushed out again and a new dryer? Or can I just pump it down and charge with the proper amount of oil in the compressor? I was hoping that someone out there has done this before?
Thanks for the input!

Love Key Largo and scuba diving john Pennekamp coral reef offshore.
The R-4 is too much displacement capacity for most Vintage Air A/Cs and avaliable condenser "real estate" space.
Early SD 5H14 (508) used SP 20 PAG which was exactly same as GM PAG 100 single end cap lube. PAG 46 (SP15) double end cap is a economic/service simplification in newer SD5H14.
Since SD5H14 come with full oil charge you need to remove oil from compressor or system. GM does not support flushing because it usually introduces weird chemistry which damages the system unless you are an expert with lots of evacuation time.
hotrodac