The 70's proved that under then current rules, you could throttle all but the best of run games. If you wanted a best offense with a running game, it had to be in college if not the CFL.

So I think its an open question whether more 60s running teams could be considered for the best offense. Even the Packers running attack was being held in check later in their decade, both by innovation (Flex Defense, preponderance of 4-3 fronts) and by age (Hornung and Taylor).