LA small block timing is suddenly way off

I will begin checking further. First a couple questions.
-- If the timing chain did jump, then would that mean my camshaft and valve train is out of phase with the piston strokes? And this could only be fixed by removing timing chain, realigning cam, and reinstalling a new timing chain? Just shifting the wires on the distributor cap to a new #1 location seems like my camshaft would still be out of time with the pistons.

-- AJ/FormS said: -One more thing, if you had a backfire during the muffler rapping, and you have a Holly/Holly type carb, then the PV may have ruptured and is causing the rough running, and again the previously slipped ring was just discovered. You might want to have a peek at the main nozzles for dribbling during idling. I do have two Edlebrock 1404 4-bbl carbs and I did have a backfire while trying to start the engine recently. What is the "PV" and main nozzles you are talking about, probably carb parts?"