Well here's what it would look like if we gave a five-point swing to McGovern. That may be too much, but if he does everything perfectly while still holding to his values and Nixon still campaigning the way he did, then it's possible.
Nixon/Agnew (R) 55.67%, 492 EVs
McGovern/Eagleton (D) 42.57%, 46 EVs
Schmitz/Angerson (AI) 1.42%
Oregon is by far the closest state in this scenario, and just narrowly goes to Nixon. This really shows just how weak McGovern was. By comparison, here is Mondale vs. Reagan with a five point swing.
Reagan/Bush (R) 53.77% of the PV, 418 EVs
Mondale/Ferraro (D) 45.56% of the PV, 120 EVs
It's interesting to see that Mondale really did do well among blue-collar voters, just not well enough clearly.