My 67 Coronet has a 493 with a 9.5 dynamic convertor with a gear vendors and 3.55. All I can say is I love the combo. Haven't had it to the track though so don't ask me for a number.

The 68 charger has a mild 406 small block with a TCI Sat night special, probably 2200rpm stall, 904, and 2.94 gears. It slips a bit more than my dynamic while cruising but still isn't that bad on the highway.
I ran it once at the track and got a 13.28 at 101 just using 1st. and 2nd.
I would say not bad for a car with a/c, power steering and lots of sound deadener.