So Nixon decides to go down with the sinking ship.
Not sure how this makes Ford a two term president. Sure, the dates work, but Nixon actually being impeached (a relativly long process) can't help him. He can't pardon nixon as in OTL without being identified with the ex-president, but even if he doesn't he is still a lame duck at best. The bottom line is, while it is mathematically possible for ford to be a two termer if the imeachment succeeds, it makes it infeasible for that to actually happen.
The republicans might be best served in '76 by nominating reagan. It was a close run thing in the primaries, and the little bit of extra stigma attached to ford may be enough to make reagan the nominee (with or without Schweiker).