Have you done some additional homework to clarify importing into the US?

Your Ultimate Guide to Importing Cars to USA | USA Customs Clearance
The process for importing cars to USA comes wrought with emission testing, regulations and manufacturer issues. A customs broker can be your driving coach.

I think you're going to run into issues even if the Japanese version comes into USA, indirectly.
The first hurdle is age requirement issue, which I dont believe your SL600 even qualifies for. (Only 16 years, possibly 15 only, depending on the month day of manufacture)