Not sure about 2016 rules but circa 2006 my friends and I worked with an importer for multiple engines. I was part of a car club and we swapped the following engines into our cars.

Honda B18C5 (integra type r)
Honda B16A1
Honda H22A
Nissan sr20det from a Slvia (my old car)
Nissan sr20det from front drive bluebird

We could even buy whole front clips if we wanted. I'm pretty sure you can import any car parts you want. Just not whole cars.