Time for the final update. I did a lot of shopping for the different options discussed in this thread and didn't find anything I liked or trusted, so nothing has been done.
After some research, I quickly abandoned the idea of finding a shop in Tijuana (where r12 is legal). Too many risks going in cold as a gringo with no contacts there.
Even though I was told by countless shops that "r12 is still legal, it just costs $110/lb and I no longer will touch it," I couldn't find a shop that actually sold it. Half the a/c shops told me it was illegal, the other half told me the quote above, yet I couldn't find a shop that still works on r12. So, I abandoned the idea of trying to fill it with r12. (Even if I found a shop that had it, the car requires 2.6 lbs of r12, which would have been expensive.)
I don't like the idea of spraying r134 cans from autozone into my r12 system, so I didn't even try. I also have not attempted to change out the temperature regulator ($40-$50 part, iirc) which I read in the forums might be the easiest fix since the compressor and everything else is working..
With a heavy heart, I've decided the best thing for me to do is sell the car. I have a couple of big road trips planned that will take me cross-country and back over the next 6 months. Even if I fixed the a/c, there is no getting around the gearing in these cars that is more suited to 60 mph than the 80+ mph I'll be travelling on interstates over 8 hours/day. I'm "buying" a Lexus LS from my grandmother that is in great shape and much better suited for the type of driving I need to do. I live in an apt. with on-street parking and can't keep a 2nd car around. :
So, it doesn't make sense for me to keep it as much as I'd like to.
I'm off to a family wedding/reunion this weekend and will be listing it locally in SoCal on Craigslist, etc. next week when I get back. If anyone is interested in the details, let me know and I'll send you the listing & pics.
Other than the a/c issue, it's a great car. 1-owner car for first 30 years in SoCal until he passed away, Maint. recs from MB dealership. Next owner put in $11,000+ to upgrade all wear items like bushings, engine mounts & front suspension & vacuum system. Have all receipts.(He sold because he and his Swedish wife moved to her home unexpectedly - he was obviously planning to keep the car - a look underneath will confirm the amount of work he did) New front brakes, brake pads on all 4, Hella headlights, oil cooler hoses, valve adjustment and diesel purge done by me. Runs amazingly well. Everything works: all windows, sunroof, cruise control, door locks. Very clean California car.