[mike55]

the disatance from the bottom of my manifold (the portion that rests on the block on either end) to the top of the velocity stacks is 10 1/2". my stacks are 2 1/4".

one thing to keep in mind, using shorter stacks might require cutting the auxilliary venturi tube. as it is on mine, the stacks barely clear the tubes.

i can't offer anything on your other questions - i'm not there yet myself and the other respondents know much more than i do about them..........

mike