But as a fan of both series; I would like to point out the fact and history of outcomes with luffy in fights Luffy defeats but rarely cause the person or things death. In which if Luffy did defeat goku in this battle and left goku alive to recover. Goku Saiyan genetics would cause him to grow even more powerful then the enemy that defeated him.
So round 1 - Luffy with Haki final round - Goku and Saiyan genetics
But in the long run I think the two would discover there infinty for eatting and a friendship would be borned