Horrendous noise after sitting for a week...

Run the engine as little as possible. Get your self a convenient scrap of about any hose from 5/16 through garden hose 2- 3- 4 ft, whatever is needed to reach, and probe around with on ear at one end

Also, start the engine cold, and run with NO belts on the engine.

Probe around with the hose and listen. I would pull off the lower dust cover as it may be hitting, and also to access the bell area. Be careful and probe up in there

Since you seem to already suspect the starter, pull it off and examing it, the bell, and the ring gear for damage. Examine for things like junk/ debri stuck in the rear "socket" where the end of the starter nose fits.

If none of that proves anything, stick your test hose down the PCV hole in the valve cover as well as the oil filler and listen, see if it gets worse.

If nothing else shows results, remove the distributor boots. Use a grounded clip lead and screwdriver, and pull out individual plug wires, and slide your probe into the distributor tower to ground the spark. Listen for a change in the noise.

As bad as that sounds it should not take long to run down.