Fastest time with a 268dur cam?!

Marcohotrod said
stock 340 cam=268/276, .430"/.444", in a 4 speed Duster 340, all stock except-750 avs, LD340 intake, headers, slicks, 2.5" mufflers, superstock springs, 4.56 gears=12.9 seconds @ 108 mph

Bingo!... and with 3.23's this would usually give a smooth idle and 20 + mpg.
pretty hard to beat the factory piece for an all round street car