Yep, seems you deciphered my rantings pretty good so far. I rechecked the dwg, and the purge valve does indeed have a larger vacuum line coming from the lower throttle body port. And it looks like a big acorn as you said.
My dwg indicates only 2 ports on the top of the purge valve, so I can't help you there.
My '91 doesn't have this configuration, and the wife has it today. But I do remember a vacuum line goes to purge or diaphragm way over in the front left corner, kinda behind the left headlight. I'm not sure if the canister is there. I can check tonight. However, in looking through the manual, it shows rough dwgs of two cars, one a 190 and one maybe a 126. It indicates the purge valve is indeed where I said, but that the canister is located low in the fender well behind the left front wheel! Which would require inner fender panel removal probably. It looks like a long square coffee can.
I'll eyeball mine tonight when she gets home.

DG