Heres my take. In my mind the '77 Habs are the best team of all time. That being said they would never sweep the Isles or the Oilers. In '76 the Habs lost one playoff game, it was to the Isles. In '77 they lost two, it was both to the Isles. This was a team that didnt even have Mike Bossy yet too! So I dont think people should underestimate the Isles. I mean before they won in '80 the lost to the Habs in '76, '77 then lost to the Leafs in '78 in OT after Mike Palmateer robbed the Isles. Then they lost to an extremely overacheiving Ranger team in '79. So they were good all those years even before the Cup. I think an '82 Isles team would be the best bet against the Habs. Maybe they could go to six games?
The Oilers best team was most likely '84. They too would be the best bet against the Habs but still wouldnt win. Fuhr is not as good as Dryden. Then on defense Robinson, Savard and Lapointe definetly beat Coffey, Lowe and Huddy. Up front Gretzky, Kurri, Messier and Anderson have the edge over the Habs. The Oilers had the best offense of all time so they'd beat the Habs in that area, but when you think of Lafleur, Shutt, Lemaire, P. Mahovolich etc.... the Habs still had the most potent offense in the league then too. The Oiers might hit seven games against the Habs, but that's only if Game 6 was won in OT by them. Then the Habs would win in the Forum.
So in conclusion the Habs are just too deep and dominant of a team to lose to anyone. They had NO weaknesses, NONE. The Oilers were explosive offensively but had a few defensive weaknesses. And Lafleur would have eaten those up.