Larry has it right about oil pressure. The pump is rarely the problem. The pick-up could be though. I would remove the subpan for an inspection. I would be sure there is plenty of clearance between the pan bottom and the rubber pick-up foot. Be sure that the rubber foot is shaped properly; it can sag and set on the pan bottom. I would also inspect the state of number one rod bearing at the same time.
These engines also almost never have lower end problems so if its bearing related it should be obvious once your in.
As to parts they are totally available. They just cost more and may have to come from MB. The only parts I would imagine no longer available would be colored interior trim.
The answer to your carb problem is to find someone who can fix yours. If you had to buy a new carb you would have way too much into it, especially if you have engine problems.
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician