Automotive Air Conditioning Information Forum

In the process of rebuilding my 1975 Corvette A/C system. So far I have rebuilt the A6 compressor with all new seals and the front shaft seal with the new lip seal type. Moving on to the VIR I actually have two of the valves. One is marked with the "E" stamp on the housing below the sight glass and the other is not. The car originally came with the valve with no "E" stamp. I was planning on rebuilding the system and converting to R134. I've read mixed reviews on other's success with the conversion. So here are a few questions.
1. Should I go ahead with the conversion or try to locate enough R12 to recharge the system?
2. Are both of these VIR's the same or should I use one over the other?
3 If I convert to R134 Is there an adjustment inside of the VIR that I can make to operate the system more efficiently with R134?
Thanks

question 3... Some of the POA's were adjustable, some were not.
question 1 I would keep it R12. there is enough R12 available. Corvettes were a poor candidate for R134a conversions. I still have some small cans of R12 and some with dye only...no sealer.

question 2 VIR's for Corvettes usually needed the top of the unit rotated in a different direction. I think I still have resealing kits for them if Tim does not have them. I should also have the TXV and POA for them again, if Tim does not have them.