I'd say, if you're going to be running BIG tires use Marlins 6 stud. Because even though the 80 stuff is a little bigger, you still have the same 4 studs holding the arm on and with hydraulic steering you're not going to feel the resistance that you are turning against and you'll tear an arm off for sure.
A full longfield set up is spendy, but mini front knuckles should be cheap and easy to come by off of someones bent housing. 80 stuff will be harder to find (not a lot but still harder) and generally more expensive.
