If Ed Muskie is still Vice President Humphrey's running mate in 1968 then Humphrey would win Maine. I believe it was one of those bizarre situation were an actual running mate brought in a state for the man on the top of their ticket. Considering Vermont and New Hampshire were then Republican states I would assume McCarthy would win them both. However, if McCarthy was running as an extremist candidate along the lines of Barry Goldwater in 1964 then Humphrey would have won them.
Anywho, here's my map for this 1968 Presidential Election between Joe McCarthy, Hubert Humphrey and George Wallace. And I can assure you that my map for this 1968 Presidential Election will look different to yours States'.Hubert Humphrey/Ed Muskie (D): 289 EVJoe McCarthy/??? (R): 183 EVGeorge Wallace/Curtis LeMay (AI): 66 EV
That's my thoughts on this scenario. Vice President Humphrey comfortably defeats McCarthy and Wallace in the Electoral College vote totals, however it's much closer in the Popular Vote totals with Humphrey narrowly winning the PV at around 40-41%. Though I have my doubts such a map like this could have occurred.