Reno- you're correct it's no "big" deal, it's just a big deal to do it right and make sure all ancillary functions continue to work (e.g., cruise control) and can still be serviced & diagnosed at any Mercedes dealer.

FWIW, before I did the C36 powertrain swap into the W124 wagon (I went from CIS to HFM, a PITA!), I contemplated doing a M117 5.6L or 6.2L swap. I had a quote from a former employee of AMG/Chicago (Scott) for about $13-15K to do the conversion.

I was ready to move in this direction until I heard Scott was found murdered, and he had taken deposits but produced no cars.

Neil