What is wrong with a MB cluster
The 140 at least gassers gets its speedo info from the ABS sensor ring on the front wheel. It is processed thru the ABS computer into a elecrical signal 9pulsating DC whic is coverted to a sine wave. The oil pressure and level are processed via a matrix and fed to the dash.
All 140 had two coils and the later had a coil for each cylinder.
The early to mid 123 had a mechanical oil pressure guage, and the tach was driven off the alternator. The fuel guage is a normal affair where you just have to match the resistance between the sender.