Nixon and Romney did not get along at all, with Romney's racial liberalism being a constant annoyance. The surprising thing is that Romney actually made it through Nixon's first term. There is just no way Nixon is going to choose Romney to replace Agnew.
Paradoxically, though, there is no reason *Ford* might not have chosen Romney as VP! There is nothing in the Constitution that prohibits the President and Vice President from being from the same state. All it says is that *electors* cannot vote for both presidential and vice-presidential candidates from the same state as themselves. If Romney agrees he won't be a candidate in 1976, there seems no reason there couldn't be a Ford-Romney administration from 1974 to 1976. True, Ford's choice of Romney would annoy some conservatives, but they didn't like Rocky any better...