We built a neat 418" 340 X block Stroker with my friend. It's in a really mint survivor T/A. Now that the combo is up and some of the small bugs are worked out.

The Combo is as follows:

K1 Based 418" Stroker
6Pack Carbs with Promax plates on an undported intake.
T/A heads with no port work and PAC 1519 Beehives and stock replacement Ferera Valves. Completely refreshed.
230/240 Hyd Roller on a 110 with .550ish lift and Hughes Roller Lifters.
1 5/8 Headers with Spintech TA Style Mufflers
A premium 3200 stall Converter (The name escapes me at the moment)
He will eventually go with a 3.91SG

We're trying to science out a bit of a flat spot as the outboards open. I'll get the jetting chart tonight and post it up. We've recently been brought onto a possible tuning issue related to the idle air bleed ports and are considering getting orifice size reduced.

When tuning out a 6pack set up, what possible mistakes can be made and what tuning process do you observe when going from start to finish?