That is a very nice piece. Very very nice.
If the runners are 5.5" long, and the mean length of the intake ports is about 4.75", then thats 10.25". At that length, you would have a tuned resonance length for a powerband from about 8,100rpm to 11,450rpm give or take. you would need to add 2" roughly to the length of the runner to make the resonance more usable for a bolt on, or modified NA application.
Mazworx, if possible I would like to know the taper of the runners. If the taper is beyond 4-5 degrees, then the taper will begin to effect the resonance tuned length of the intake runner. The wider the taper, then the longer the runners will need to be for the same effective resonance tuning.