You should have enough clearance with a smaller cam. But your clearance comes into play just as much with the advance or retard of the cam when you degree it. The more the cam is advanced the tighter the clearance on the piston. Therefore you could have a 725 lift cam with less piston clearance than a 748, if the 725 lift cam calls for a 107 centerline and the 748 calls for a 110 centerline. If you change a cam, I think you should always have your clearances checked. JMO