Converted one of my trucks (86) from R-12 to R-134. Spent some time twiddling with the pressures, seeing how cold I could get it. When I got it to frost the windshield and give me brain freeze on a hot summer day, I figured it was working quite well.

In just about every application of a conversion, I've found R-134 to be capable of getting very cold.

'97 T-100 SR5
'86 Toyota's, the variety pack (all gone)