Hi Eric,
That question cannot be answered without knowing the US model year and possibly the specific VIN number.
The assumption that US is US cannot be made in this case, since some signifcant changes where made during the production years of the 280, especially regarding emission control. Take a 1971 model, for a start it would need a euro throttle body and distributor to get rid of the US emission control stuff. Then the camshaft and I believe also pistons are different,at least on the later model years.
A US 1968 model would be much easier task, since it lacks most of the emission related stuff found on later cars.
Regards,
Hans