Well, to take 600hp neither one will be cheap.
The 904 will cost extra money to gain the required durability, where it's a little more "built in" in the 727. A few here say there is only a 15-20 hp difference between them at the tires.
So I guess the question is: How much is 20hp worth to you? A few of the more experieinced guys can give you a better idea.