For a 2018 Morgan you need to research the Epa and Vehicle safety standards. Before it clears customs you may have to prove it is "clean and safe".
In 1976, before the 25 year rule, I imported my +8. I had to modify it to meet 1970 US standards and prove to the EPA and the Federal Motor Vehicle Safety people that the work had been done. It sat at the port for a month while the wheels of government slowly turned. I had to show the customs officers how to handle the importation.
