The problem Nole would have against a prime form of Fed is mostly the match-up- Olderer form had match points against him in New York and beat him in RG because his variety gives Nole trouble. The old form of Fed possessed not only the serve and the variety, but probably the best forehand I've ever seen and the ability to just destroy opposition off the bat.
Murray can count himself quite lucky he's playing now and not when Roger was peaking cause I think he'd absolutely pulverise Andy across the board.
Nole, would play more agressive against that Fed, like he did in Montreal and the first 2 sets of the Uso final (both in 2007). Fed would still win more than Nole. But matches would be close, except on grass were Nole wouldn't stand a chance.