454 crank comp height 1.645 396 -402-427 1.765 so if it is in the hole 100 or bit more but the crank counterweigths on the 454 crank may need a bit of work .i thing it can happen with the 396 shelf pistons cut just the flat of the piston and the dome will go up more so more cr but the valve notch will have to be fly cut in more or the big cam