I hate working on AC...
Watch your tail on buying a compressor. There are at least 3 different ways that the compressor can be setup on the 85-94 22RE. Two different styles 86-88. They don't interchange with the bracket.

IF you get in a bind, ping me - I may have the bracket you need. I spent time chasing one down. I bought 3 before getting the right one.

Might check with rockauto.com - make sure they come with the compressor clutch.

The 134a conversion kits that I see typically are O-rings. I'd talk to an AC shop about it. After 20 years, it's probably a good idea to replace all the o-rings anyway.

Personally, I'd get the new compressor installed, assuming you trust the pep-boys diagnosis. Have it charged and professionally leak tested by an AC shop. AC leaks are hard to find without UV. The right way to do it is to evaculate it and see if it will hold vacuum overnight.

Yes, you can pull it from under the motor.