Compressor failure can contaminate the entire system with debris that will damage or ruin your new replacement compressor. I would have the evaporator, condenser, and lines professionally flushed before replacing or rebuilding your compressor. Then, be sure to use a new dryer (accumulator) when putting it back together.
There are DIY flush kits, but I took all my components to a local shop, connected them together, and asked them how much they'd charge me to use their pro equipment and flush it. $20 and done! I couldn't have even bought the DIY supplies for that.
Don't recharge the system without THOROUGHLY vacuuming it down.
Do you have a source for R12, or do you plan to use a substitute?
I can't offer advice on compressor brand and size--but maybe this will help get the conversation started.
Jack
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'83 Isuzu P'up Diesel LS - Original Owner
JoeIsuzu@IsuzuPup.comIsuzuPup.com