I lowered the low side pressure to 40 and the high side came down to 155. It's now cooling very well. 44 degree output air at 85 degree ambient outside temperature.

I should have mentioned that while the system has been converted to R134a, I charged it with Enviro-Safe, a brand of HC-12. I've used this on a number of cars with great results. It cools better than R134a and runs at a lower high side pressure making it a little easier on the compressor. Plus it is compatible with mineral oil and the original seals and "o" rings. Just change the charge fittings and you're good to go.