how far up and down can you go on the primary ports of a s4 n/a ? is it better to do a box end or round ? im looking for it to open asap (so i will bridge) and close at the latest with out any interferance with other parts could some one give some #'s or tips

 

I have a hafe engine for display so as able rotate the rotor and see where it going to be. all it is is a 12a with the shaft cut in the center. just spin it around and see where one can cut, junk engine are easy to come by.