If you have been bitten by the "go fast" bug, my advice is to leave it as it is for now and start looking at stroker kits. Whether you simply go to a 3.75 stroke in your 383, or opt to find a 400 block and push out to 470 cubes or more.... You'll be happier in the long run than just trying to squeeze a little more out of the numbers matching 383, because that's all you're going to get with that plan; a little.

A 470 could be built to idle easy and be just as drivable as you are now, but still stomp every cammed up 383 you will run across.

And by the way.... In order to qualify as a "sleeper", it has to actually be fast. An E-body flashing RT badges and running 13's is not really a sleeper in my book.