383 question

Quote: I just want to make this motor the best it can be with bolt on stuff an NO major internal mods, except for maybe a camshaft change. Plus, I figure in a Dart, 450 HP is more than enough to make a wicked ride, right??!!

If it was me and it has been for years since I've always had a soft spot for 383's (so much potential) I would do 2 things before touching the cam. Yes to a 750 DP'r (you're going to be there eventually so might as well start with one) and either Crane or Hughes aluminum roller rockers which would require custom length push rods. The Holley is a good manifold not as good or as high (1" at the back) as the M1 but like all single planes can be doggy off the line, you can counter that a bit with a 1" thick 4 hole spacer. Now the rockers. The stamped steel rockers are crap for ratio accuracy. The last build I used Hughes and before installing them I rigged up the old stamped steel set with a solid lifter and adjustable pushrod. This allowed me to see with dial indicators, the actual push at the valve stem taking the stamped rockers into account and taking the spongeyness out of the hydraulic lifters. The end all be all is that the old 1.5 ratio steel rockers were actually between 1.40-1.42. I then latched onto a pair of brand new mopar steel rockers and they were almost as bad.
So I'd go for the carb first then the rockers and get some before and after times. I was going to do the same but our track shutdown.

While this is all going on you also need to pay attention, as Rob says, to your torque converter and it's sweet spots.