Air conditioner

1986 4Runner. 265,000. This problem has been unsolved for over a year. I have very high low side pressure after only about 6oz. It gets up to about 60-70psi and wont let any more R134 inside. Can stops getting cold and nothing else flows out. I’ve replaced the compressor and clutch, expansion valve, accumulator, condenser, evaporator, and pressure switch. I did an individual flush on everything but the compressor. Then put a vacuum on for and hour and then let it sit for another hour with no leaks.
When I start the truck and start the a/c, the clutch engages and seems to be working fine, but will only accept about half of one can and that’s all.
So I'm stuck with a completely new a/c system that does not blow any cool air.
I consider myself vehicle savvy with a good deal of a/c knowledge after a year of continuous work, so I don't have any idea what a mechanic even might tell me. Any thought would be great. Thanks