Two things about 124 vs r 12
It is not as efficient
I replaced the condenser in my truck with one from a dual air 68 van
second 134 will leak in places where Freon will not that's why they went to dual barrier hoses and better seals
an aux fan will help in stop and go driving
I have mine where it turns off at 30 mph
a test is to put big shop fan in front of your ride and turn it on and see if the AC temp drops- mine did