Yup, single pattern. Why dual pattern? As Isky cams explains in his Tech Tips, it is from habit. The factories often used DP cams. The most logical reason is that the cars had restrictive exh manifolds, restrictive small diam exh pipe sizes & restrictive mufflers. So the exhaust needed 'help'; enter, extra exh duration.
A performance build has free flowing headers, large diam exh pipes & mufflers [ if used ].
Mother Mopar has left a history trail for us with the 63-64 Max Wedge engines that had factory headers...& single pattern cams.
