Did you ever inspect the thrust plate behind the camshaft timing gear? You can see it through the holes in the gear and maybe from the side with a flashlight.
You need to make sure that the screws which hold it in place are there and tight and actually going through the holes in the thrust plate.
I just got done tearing down a 235 which was parked by the previous owner soon after a re-ring job because of a "horrible noise" (his words!).
I removed the 2 screws which hold the the thrust plate to the block and removed the cam to find that the screws had not been installed through the holes in the thrust plate! The ears of the thrust plate were completely broken off. No wonder it made a "horrible noise".
