Is your block a 426 street wedge or race wedge block? If it is a race block it will have the exhaust valve reliefs already cut in the cylinder walls so the max lift shouldn't be a real problem with most solid lifter race cams. That is one of the things that always need checking when changing cams just like valve to piston clearances I have cut those exhaust valve reliefs in 426 Street Wedge blocks also for max wedge heads and valve to block clearances