You could try limiting the mech. advance by welding up the slots inside the dizzy. When does the dizzy reach full mech. advance? If its fairly early, you could also try one heavier spring inside.
...or it may be all carboned up. I'd try the "drip water down the carb while revving the snot out of it" method.
the plugs are autolite 85 which is the correct plug for an hp 440/383.the advance is all in by 2600.i thought about welding the slots in the dizzy,but still,having to limit total to 22* ?ill check for carbon build up.