r134a conversion
 

Would you just use a regular r12 compressor if your converting to 134a?

Yes sir. You will need to add the proper amount of 134a & compatible oil. If you buy a retro fit kit then you should be good to go. Make sure not to overcharge it as 134a runs at higher pressures than r-12. It would be a very good idea to vacuum (pump down the system before you add the new refrigerant) If you have access to a pump.