[Michael C Henry]

The heads will make one of the biggest differences . The engine is a package and if any part isn't up to the task, that becomes the limitter . Most componets have a designed operating range heads ,cam, intake,exhaust .I once had a 406 with different parts It wasn't that good at any one rpm range ..Also with a 428 you get a longer stroke for more torque but you trade rpm potential.It's all your descion, performance ,releiablity, expense.Weigh all elements because you have to live with the outcome.You don't want to redo this again.