A fist fight?
This can very easily go either way, in my book. At their peaks they are both near the same age. They're both very strong and durable and neither of them have a problem with fighting dirty. I'd say McClane can take more punishment but we've never really seen Indy pushed to the breaking point but he always takes major abuse and like McClane he always has something left in the tank. They are both just as resourceful as one another and just as quick thinking.
I think 7/10 this goes to who ever is having the better day but remembering the truck sequence in Raiders and the Tank sequence in Crusade i am inclined to say that INdy is probably going to have more good days than McClane. I do not think McClane could have done what Indy did in either of those scenes. This isnt a battle of feats though which is why i say it could go either way.