Cervan, man go take a valium.....or find a large wooden mallet and give yourself a quick whack in the noggin or two.
This is much crazier than the accura engine thing.
The old 671 jimmies were cool sounding motors, they screamed like a v12. Of course back when they were in vogue I did not know what a v12 sounded like but I knew I loved to hear them wind out.
A 371 is out too, the weight of it would totally mash the front end of your benz.

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Just getting a benz running nicely in stock form is quite a task for most of us.
Tom W
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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.

[SIGPIC]
..I also have a 427 Cobra replica with an aluminum chassis.