Yes, I know the winner of such a conflict would have a lot of variables, so let's simplify it.
Kennedy not assassinated, no Vietnam War, no New Left. Cold War doesn't show any sign of stopping.
June 1st, 1975. For whatever reason, World War 3 starts between the two blocs. The aggressor is debatable enough that morale is high on both sides. Conventional warfare only.
Who wins?