If you do decide to go with that hydraulic roller cam, mock up the block, heads, cam, lifters, push rods, rocker arms, valves, and springs before you final assemble the engine. Because you will probably need to grind some clearance into the block and/or heads for the pushrods due to the taller lifters. You don't want to discover that after the engine is already mostly assembled.

Don't worry about the head nuts in the valley. Just get an adapter and do the math like shown in this thread:
https://board.moparts.org/ubbthread...0767/re-426-hemi-head-bolt-question.html