[Jack Houpe]

Just seen this thread and yes your low side is too high, evaporator temp at that pressure is 65 F, should be 35-40F. I would rather fix the old one or retrofit something else below than loose real-estate on the roof top, you will find the roof top units can be a pain in the rear. Remember you'll have water running off the roof all the time unless you can find a drain plus having to run electrical to it from the panel without messing up your beautiful inside. But if your going to d0 it Dometic makes a inverter roof unit.

https://www.dometic.com/en-sg/outdoor/sg...r-_-152020

I just built a freon recovery system, I had a good 120vac compressor so I silver soldiered the high and low sides closed and put line taps on them, then I took the valve out of an old propane bottle flushed it out with lacquer thinner and made a manifold. It worked wonderfully on the 24vdc AC system in our van, I had the compressor mounted under the van but decided to move it to inside for safety.