Just rebuild your original RV-2 and buy a NOS expansion valve. If you look into the end of it there is a spring with a hex sleeve for adjustment. I am going to tighten that sleeve to put more pressure on the spring 1 turn to compensate for the R12 in the NOS valve and the R134A saturation temperature. I used a NOS front seal as well and it held a vacuum for 24 hours without dropping at ALL. Never seen that before. So bottom line all the crap about needing to "change over" to 134A is crap. I spent a lot of time learning AC and thermodynamics in the last 2 weeks and now understand it. New green o-rings on the lines and that one small adjustment of the original expansion valve is ALL you need to do. Then only fill it with about 80% of the R12 fill number.
