On a Street Dominator (similar to the M1) I always make the #1 and #7 roof a slightly taller Trapezoid (Gumby's head, I call it) than the port next to it in the plenum (in this case #2 and #5 respectively) that pulses before it. It seems to work really well judging from before/after plug readings where #1 and 7 were a little lean.

In a single plane with adjacent firing holes the first fed tends to be the best fed on many Siamese port heads and intakes. An old NASCAR guy taught me this many moons ago.

I used to have some shots of my SD mods (in rough, unfinished form) that illustrate it but I think I conveyed the Gist of it.