The map as drawn is somewhat later than the Revolution. That shouldn't be a problem in building a good border here, should it?
Know that Maine, as OTL, was part of Massachusetts for a time. Note also the existence of the state of Superior beyond Quebec. That's another point with which I hope people can help me. Its borders are contingent on Quebec's, so I'm putting that off for now.
Ontario at point of Revolution was not a state either, but became one relatively soon afterward (the story in question is The United States of Ameriwank).