I still have 9 lbs of R12, so I'll just stay with that for now, but my car won't idle with the a/c compressor on.  Just drags it down and it dies.  I've tried to use the idle stop solenoid (anti-dieseling solenoid) as an idle bump up solenoid, but it's now really designed for that.  Car is at a hot rod shop right now to figure out my carb problem.  Maybe that will solve my a/c idle problem too.