[Keithc8]

When you say brand new 351W with stock pistons, do you know what piston it has. If you could find out it would help. There may be a part number on the piston. The piston to valve clearance I feel would need to be checked with either head. The AFR heads have the piston closer to the deck than most heads and this puts the valve closer to the piston. I will try to help anyway I can. Good luck, Keith Craft