Polling the group:

What is the recommended or optimum runner length for the primary and secondary intake paths, optimized for 6000 rpm (2.17 redrive and 2700 prop rpm is the plan, with boost).

The plan is to use a cut-off portion of the stock lower intake from a 2nd gen (mates to the block and changes the intake path 90 degrees). Attached to this will be intake tubing  (approx 1.5" dia for the primaries, 1.75" for the secondaries) that will run to a stock throttle body. The primaries will merge into one just before the stock TB, just as in the stock manifold. The secondaries will each remain single (again as in stock).

Dave