Hi Fred,the first sale @ $100,000 was definately Suss ,but it did sell later to a genuine buyer,thankfully,the Seller was merely speculating but we both know the arguments that caused.
Regarding the 250...yes it is a troublesome engine,back in the day they were known for either breaking the crank or running bearings.There is a series of modifictions listed in the mercedes Workshop manual updates.It would be highly unlikely after almost 40 years for any of these early engines to be still running .
The stick shift in any Mercedes is a novelty at best and can be a bear to drive in traffic.