In NB if you cross at Evandale you will have to cross again to get to Gagetown and there WILL be a lot of serious climbing involved. If you WANT to go through Gagetown (very lovely village), it would be best to stay on rt 102 from Saint John and follow the Saint John river all the way to Fredericton. The roads are narrow with little to no shoulders but not very well traveled by cars until you get near Gagetown. Moncton to Fredericton is a nice tour on the back roads with only about 30 miles of sub-par roads of a roughly 100 mile ride. IMO I would not consider the Campbellton route because of the climbing (Miramichi - Campbellton) Where in Quebec are you going?