Wow, all that on a 216, what a deal. Mr.G, your list doesn't say plug wires, but I'll bet you actually replaced them.
I would doubt the five pound difference would be detectable, and although I have never even seen one, the rebuilt carb would be my first suspect.
If you can verify no vacuum leaks anywhere, and the idle smooths out as the RPM's are brought up slightly, it would sound like a idle circuit problem in the carburetor.
I would make sure the wires are indeed new. You could let it idle rough for a couple of minutes, shut it off a take a peek at the plugs..you might find a surprise.
If it is smooth under a load, say lugging it up a hill, the ignition might be ruled out.
A "idle only" problem usually screams vacuum leak or idle circuit problems. Keep searching!
Stuart
