Phil. The Top of the longerons ???is the normal thrust line. I do remember a number of builder changing , including me. I lowering my thrust line about 1 1/2 inches below the longerons to allow the twin top mounted carbs to fit under the cowl line.
But One of the Famous Mark's Brothers, sorry (Mark L and Mark J ) would be a much better adviser than I. Phil Matheson SAAA Ch. 20 VH-PKR Australia EMAIL: phillipmathe...@bigpond.com KR Web Page: www.philskr2.50megs.com http://www.vw-engines.com/