Mercedes came up with the 230 which had an M180 6 cyl. Several modifications were done, the radiator was moved forward and an expansion tank used. As for you performing an engine swap, a modern day V6 or V8 would probably fit. You would then have to use the rear axle from a 280SE 4.5. Your idea of an M102 is a good one if you want to keep it all Mercedes.

__________________
Regards

Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.