If history proves correct/reliable, it takes the average team a year to overcome the nuances of a new car design/body style change. While the benefits in the long term may be attractive, the $12-$15 Million per year the primary sponsors pay to have their name on one car isn't "patient money". They want to see their car in the winner's circle as often as possible. That doesn't happen when you're trying to figure out setups for each track with a new aerodynamics package, not to mention the new coil-bind front suspensions in the COT's they're running now.
I think any changes the manufacturers make or initiate from this point on will be well thought out and timed to benefit the teams' learning curves.

To answer your question a little more directly, yes, Ford did enjoy success with the late '60's model stock cars. Then Dodge and Plymouth had everyone covered with the Daytona/Charger and the 426 Hemi in the late '60's into the early '70's. That was when the King really started to dominate every track, every week. 200 carreer wins says a lot in a sport where the next driver had fewer than half that. That's real domination.