Are you going to use it on the road? If so it needs to be road legal - blinkers, two mirrors, horn, stop light, head and tail lights ... Note while our 'roads' include may miles of dirt roads - these too are clasified as legal roads and you need to have a rigistered vehicle to use them. Unregistered vehicles can only be used on private property (or in a few rear instances with special reistration on public land).
Note this is not a customs requirement - they want 1) clean 2) any import duties that may be due (unless you have a carnet).
Regards Frank Warner
motorcycles BMW R80 G/S 1981, BMW K11LT 1993, BMW K75 G/S