Warsaw Pact nations had shit economies, they wouldn't have been able to sustain a longer war. In a conventional war, i feel that the both sides would be very equal in military terms, the only real advantages would be that NATO forces would have air superiority (If not supremacy) almost immediatly, while the Warsaw Pact nations would be able to bring in their full might much quicker than NATO (Ferrying sizeable amounts of US troops would take a couple of weeks), until then all that would be trying to hold back the Warsaw Pact would be Germany, France (Depending on year), Italy, the UK, NL BE and Spain (Again, depending on year) on the mainland, and Norway all on its own up north.
So, i believe the frontline would become static, somewhere in Germany - Northern Italy, at which point having a strong economy to keep war production up would be neccesary, something that NATO countries had an advantage of.
Also, there is the point that many people within Warsaw Pact had many dissenters, since communist regimes where not particularly well liked, thus presenting several Warsaw Pact nations with another disadvantage. NATO countries did have the same issue (France for example), however not to the same degree.
This is all considering nobody used tactical or strategic nuclear weapons.