re: If Archie ever had an offensive line to speak of,

I don't know that it's possible to achieve "greatness" at the QB position so I would not call him a great NFL QB, but he came as close to doing so as one could do. Opinions may vary but the honors he won in 78 and 79 are facts and they strongly support the view that he was a well above average NFL QB. Admittedly, you get into "eyeball tests" once you can past that sort of evidence, but here is something to consider: Manning was a starting QB in the NFL for well over a decade without winning, including with the Vikes at the end. This didn't happen with Steve Spurrier, Terry Hanratty, or some other college greats who struggled at the NFL level in the same era.

Numerous players and coaches in Manning's era considered him an upper echelon QB. I can see where folks such as Fox are coming from (primarily stats), but I will go with what I and Manning's NFL contemporaries saw.

A little off topic: how much fun would Manning have had with some of these modern offenses? His arm and athleticism would have served him so well.