He would've definitely been better than Carter. By '76 he'd stood up to some of the prevailing detente conventional wisdom & would've been much more prepared than Carter as of January 20th, 1977. Carter took about two years to get some sense, a learning curve Fird had the advantage of having had in his first term. Hell, he'd probably be more popular with the Democratic-controlled Congress than Carter the outsider ever was.
While I oppose detante as much as everyone, I don't think it would have been a good idea to confront the Soviets in the 70s when our army was only number one in doing smack.
I have to agree about congress, though. It is far easier to unite barely reformed segregationists with strong conservatives that it is to united barely reformed segregationists with New Left pinkos.