Usually kits go the other way around, from the US to Canada. I can't imagine it's much different though. Pay the taxes at the border and everyone is happy.
I just did this with a wing kit and it was reasonably painless. Had to fill out some forms at the border but no taxes. Not sure if this would be different with a larger import (more than one sub-kit?) but call the cbp that you will be transiting and run it by them.