W115, USED Diesel Engine

One thing I've never tried to mess with myself is A/C. The mechanic who recently checked out my non-functional system said the compressor was ruined because a previous owner had converted it from R12 to R134. This didn't surprise me, based on what I've read on these forums, but what did was his categorical remark that replacing it with a used or rebuilt compressor wouldn't do. That struck me as unrealistic and perhaps also just mistaken. Can anyone with experience with used or rebuilt compressors confirm or deny whether these are a viable option on old Mercedes?

I have a chance to get a brand new 30 gallon drume of spindle oil. Will this burn in my 300D? I was thinking 50/50 with normal diesel fuel? Will it work? Problems? Thanks!!

Installed the auxillary fuel pump and it works greats. My question: I also have a marine style bulb hand pump installed, when I bypassed the stock hand primer pump last year. Should I remove it? Can it handle the pressure the auxillary pump produces? The bulb pump seems pretty plump but it's holding, no leaks. Will it eventually burst or can I just leave it alone for now? I'm planning on a 700 mile road trip next weekend and would like to wait to replace it if I can. I've ran about 150 miles since I've installed the auxillary fuel pump and no problems. Thanks, Keith