Is the cam timing the problem, or something else?

Some good clues to poor performance here, especially the first and last ones. I would start with ignition timing and carb...tune it good first. That's not to say the cam timing is or isn't an issue, but I've had 440s that couldn't get out of their own way because the ignition timing was late and the carb wasn't right.
I have gone that route, as well as swapping the ignition over to factory style Mopar with no improvements.