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Well, I got the engine back together and running after an extremely helpful MB mechanic in KY got me a LH cam, bearings, and rockers at a good price, and, shockingly, all these parts were in excellent condition after 115K, even the rear lobe of the cam (the donor engine itself jumped the chain and bent valves). He marked all of the parts in order for me. I was worried about the cam being bent but it went on with no problems and spun freely after torquing.
I went crazy cleaning the cam oiler tubes, even to the point of making a 1500 grit "sandpaper reamer" and I got the insides mirror-smooth and flushed the heck out of them - after I was done, they were surgical theater clean. Then I blew them out with pressurized brake cleaner fluid and rechecked. The manual says "replace if plugged" but I'm confident that I got them totally spotless.
As to the original problem...well...I probably will never know. I know that the PO had allowed the engine to be abused to a degree, and it's possible that the rear LH bearing got progressively worse (the rear cam lobe was not good when I bought the car, but I decided to live with it), which blew the oil film, heated the bearing up, melted the fitting, then the other bearings got bad also, then all of the other fittings melted and the lobe/follower surfaces were damaged.
Some observations:
1. If you don't have a solid stream of oil at idle hitting the RH front cam lobe (visible through the oil filler) at idle with the car cold, something is really wrong. I think the lack of back pressure on the LH side made the RH side pressure lower, making more of a "drip" than a stream. Enough to keep everything lubricated, but still, not right.
2. DO NOT EVER IGNORE a "new" noise. I'd guess that I was 10 miles from diasater. I couldn't turn the old cam in the old bearings by hand. I'm sure I wasn't far from a broken chain, cam, or plastic guide, and failing at speed this would be an automatic engine replacement. There was a lot of aluminum transferred to the surface of the cam journals.
3. I did notice that when this problem started, the oil pressure seemed to take 1/2 a second to come up entirely when the engine was cold started. Usually, this is was absolutely immediate on this car.
3. One of my personal victories that came with maturity was becoming patient and methodical. I am not a mechanic by trade, and doing this work is not second nature to me (yet). To protect myself from accident (and a boo-boo in this area would become very expensive very quickly), I do things by the book. This includes:
1. Cleaning the bolt threads and oiling them
2. Cleaning the head/bearing mating surfaces
3. Liberal use of assembly lube
4. Stepped torquing in the order as shown in the manual, SLOWLY
Basically, one stripped thread in this area would run about 2K - the cam bearing bolts are head bolts.
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