Well, I'll add a couple of things to the discussion.
R-134A will work fine in these cars if you replace the stock condenser with a parallel flow type. The condenser is what keeps the stock setup from working as well with R-134A.
Freeze12 and R-134A don't seem to function any differently in these cars with the stock system. Both will cool the car pretty well. However, R-12 really seperates itself when the temp is above 95 from Freeze12 and R-134A. And Freeze12 also seems to run at higher pressures, pretty much a mirror of R-134A.
Take this into account: My wagon had reman compressor, new rec/dryer and exp. valve, system completely flushed with new orings/Nylog. It couldn't get vent temps below 55 or so when the temp was over 95 degrees, which it pretty much was ALL last summer.
Also, with the temp in the 70's and 80's here recently, it does get down into the mid,high 40's at the vents, but it doesn't do it as fast as the 240 on R-12, and the 240 gets down to 40-41.
This is
First Hand info.......