The conversion process would probably cost more than the car is worth if you could even find a shop who could do the work correctly IAW all the legal requirements. Back in the eighties it was common for new and late model used Euro models to be "converted" to US spec by a cottage industry, but it turned out that the process was riddled with fraud. The roof collapsed in the nineties, and a number of "conversion specialists" were convicted and served prison time (One had a shop in Hermosa Beach about a mile away from my house), and many owners of so-called "gray market" cars had them confiscated by the Feds with little recourse for recovery.

IMO forget trying to convert a 12 year old car to US specs. You're better off finding a US spec 300CE and having it converted to a five-speed manual if you really want a manual.

Duke