WinSPMBT

[Marcello]

It would be nasty for any germans running into them but they would hardly be invincible. The the side hull and the rear should be vulnerable to several high end german weapons. Besides there would not be any ammo and spare parts for them in 1944 and they would need them soon. They would not be able to do much more than the B1 bis at Stonne or those KVs during Barbarossa.
The Nimitz in 1941 on the other hand would probably be able to win the war in the Pacific by itself. With its conventional weapons arsenal and historical knowledge it could have wiped out the bulk of the japanese fleet without breaking a sweat and if it carried nukes onboard Japan was in a world of hurt. All of this before spares shortages would have become an issue. Submarines would have been pretty much the only thing capable of touching it and the odds would be against them.