I think it might help Nixon win Texas and could possibly flip Louisiana, Connecticut (Bush's father was from CT and might have even helped Nixon win there) and Maine (due to Bush's moderatism). other than that, Nixon could not win anywheres else. Maybe if he chose Prescott instead, he would have a bigger amount of states that he could win but otherwise, the most he can get 348 Electoral Votes.
Maine went to Humphrey because of Muskie. A VP candidate who's moderate wouldn't flip it. Spiro Agnew was viewed as quite moderate too.