Chris,
First thing, thanks for the off-FORUM suggestion on runing your VIN on the Russian WebSite. I ran a couple of ours and it came back saying that we have leather seat covers... NOT !

Back to the engine/tranny vacuum control for your new/old 300D Euro... which IF your VIN info is correct, probably is a 1979 model... agree?

If I remember correctly you haven't yet resolved all of your vacuum leaks and/or component failures... what about your 3/2 [aka switchover valve] problem. My point is that I would first go through the engine/tranny vacuum control system line and components... clean the line(s) internally and each component, replace any that are clearly miss or not functioning properly, then take a look at the vacuum being delivered to the tranny's vacuum modulator while driving the car. This vacuum signature needs to be just under 20...~15 lets say and smoothly reduces to ~zero at full throttle.

IF we don't have something close to this as a signature, then we need to definitely remove and clean that unusual VCV on the side of your not-so-usual "MRSF" injection pump on your car. I told you that we would have to go very much "tongue-and-cheek" with your "Euro" model ! I have recently disected an old VCV from one of our cars and feel much more confident that I can help you deal with yours IF it is not properly doing its job to create and send the proper variable vacuum signal to your tranny.

Finally, to my way of thinking IF what you mean by "shift points" is at what speed and/or RPM it shifts, then this is the modulator on the tranny... but again we have to get our ducks in order and make sure the rest of the engine/tranny vacuum control system is working properly first... including a check to see just how large any restricted orifice is in the vacuum tack-off at the main vacuum pump -to- brake booster line! This should be less than 1 mm. dia. If you have a caliper, you can gauge the hold with different size needles until you find one that is "snug" and then check its dia. with the caliper!
Regards,