Detiron,
I know..., I thought you mentioned 6 cyl in your email. Good luck with finding your dream machine.... what do you intend to do with the existing M40?
Mine is a 316i M40 without catalytic converter, what about yours does it have a catalytic converter?
I am sure you have checked if this M50 has the EWS system or not, cos it may come in conflict with your E36 M40 if its 92 model which does not have ews. You may also need a six cylinder front and rear anti roll bars, engine mounts, instrument cluster, and ofcourse the exhaust in addition to the ecu and wiring loom.
I think the asking price is a bit too much for the M50, considering these machines were made 15 to 16 years back (last produced in 1994), plus not huge diff in the HP if going for the B20 version when compared to M40.
Yes the M50 B25 would give you tremendous difference!
BMW Heaven Specification Database | Engine specifications for M50 engines
Regards,