you are probably familiar with the posits about the remnants of the Greenland communities, driven out of the area in front of the mini-ice age - who may have threaded thru the waters of Canada and the Great Lakes and ended up assimilating with the Mandans and others?
I have my own theories about the Norsemen and the People of the Longhouse - upper N.Y. - Onondagas, etc. The very Viking looking longhouses? And the Native Americans who were taller than many other clans?
It has been frequently commented that Eastern Woodland Indians have facial feature that are distinctly European.
I wouldn't have any problem with contact, even 2 way contact.