I don't recall OVP status on a euro car, but the OVP would have to affect the lambda control unit to have any effect on running and your car doesn't have lambda control. Your system is virtually the same as the US 450 K-Jet system. The US cars with OVP have K-Jet w/Lambda (frequency valve controlled lower chamber pressure) or KE Jet after 1986.
I would presume that you have ABS and the US cars would have the ABS controller also powered by the OVP but then US cars didn't get ABS untill 85, so I don't remeber how the ABS controller on your car was powered (but it wouldn't have anything to do with running anyway).
Bosch Master, ASE Master, L1
33 years MB technician