Here's a straight six in mine .... Ford 300 punched out to 313, Porsche carbs, custom intake and now has straight cut timing gears. There's just somethin' about an inline motor .....
Probably the best inline-6 for oval tracking. My buddy built one that would give the V-8s a run. He'd turn it 8,000rpm. Roller cam, roller rockers, Holman-Moody intake manifold, etc. I have a Vertex magneto w/dual tach drives for a 300 six. It'll be on the parts forum here in the near future.