The tall deck requires a longer distributor shaft from the lockdown collar. If you use an MSD and some other aftermarket distributors they have an adjustable slip collar on them. Drop the distributor until it bottoms out on the oil pump drive then raise it up 1/16" and lock the clamp collar. some manifolds come counterbored for the tall deck but they require a spacer for a regular 9.8 deck block. Tall deck is 10.2 height.
Hope this helps.
Zip.