[WDCreech]

I remember reading, years ago, to run a dual pattern cam with D-port heads and a single pattern with round ports. But as Skip Fix stated, it all has to do with the flow ratio! I was running '68 RA IIs when I read this and have used a single pattern cam since with RA IVs and Wenzler High Ports. For D-port engine, I would look closely at the intake/exhaust flow numbers.