cam
The problem isn't the cam it is your heads, I have built several 383's but I use either 346 or 452 heads that I port and install lager 2.14 and 1.81 valves. They will flow in the 280 cfm range. I recently did a set for a customer we put on a .030 over 440 in a full body 67 GTX at 3988 lb. that ran 11.60 through the exhaust with 8" drag radials. If you have any questions call 724-791-2514.
Thanks, Bruce