Larry,
Why don't you simply import the manual trans conversion parts for the Benz of your choice from a German junkyard, buy the car here in the US, and have it converted by the tech of your choice, or do it yourself. It would be cheaper and easier than importing a "grey" car, and the stronger bumpers and better rustproofing on the US cars are an advantage in most cases. A few years ago, I converted an Alfa from Spica mechanical fuel injection to dual Dell'orto sidedrafts. I obtained the complete setup from an Italian salvage yard, bolted it on, and a temperamental car became a really quick, fun, simple, and dead reliable daily driver. Just my .02.

Colin Connor
'71 Triumph TR-6
'72 BMW 2002
'82 Volvo 245
'82 Moto Guzzi 500 Monza