Do you mean the first game in the all seater stadium, with Steve Whitton scoring for us (I think...).
If so, Best and Charlton had been gone from United for about a decade by then.
The big win against "that" United team was in about '68 when Chris Cattlin made his debut marking Best. I think that was a 2-0 win - I was too young to go to games in those days...........