You are, you just don't know it yet The length of the runner is all about frequency tuning. The length determines the timing of the returning pulse. Longer puts the return at a lower RPM, at the expense of high RPM restriction (function of CFM though a given size).
6" from face of head to inlet of runner (including the velocity stack).
Keep in mind, my prototype was built for a show car first and foremost. The difference in performance between a 6" runner and a 7" runner would be minor in this case, but the effect on appearance, with this particular manifold, would be pretty dramatic. A compromise was made at 6". Otherwise, I think a 7" runner would have been a better choice.
Also, in retrospect, I believe the 1.5" runner was a little oversize for the cam we settled on. A 1.4-ish runner would have bolstered the bottom-end with no loss on the top (and quite possibly would have shown a gain).
Its commonly taught (and mirrors my experience) that runner diameter is the single largest influence on where the torque peek falls. Runner length, in normal scenario's, seems to have more impact on the area under the curve. In other words, how flat or peaky the curve is.
Keep in mind manifold design is both art and science, and a person could invest an entire career in manifold design. Its not always black & white... and the 'intuitive choice' doesn't always prove so.