Try asking the guys at Clifford Performance. The are pretty much experts on the inline sixes. Try
www.clifford performance.com or call them at (909) 734-3310. I hope this helps (sorry if you have already tried them).
stefan
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66 Standard coupe
200 inline 6 - Pertronix ignition, K&N, Clifford Perf. 6 into 2 headers(not installed yet), Holly carb
96 GT Convertible
K&N (more to come)