[Marshall V. Daut]

Normally clutch and flywheel noises begin when the clutch pedal is depressed. You have the opposite problem. Check that the front of the engine isn't dipping too much, allowing the back of the crankshaft pulley to strike against the Y-shaped front motor mount. That will make a metallic clipping sound. Feel the back of the pulley spokes to see if you can feel divots dug into the back of them.
As you push the clutch pedal in, there is enough wear on the rear main bearing thrust surface so that the crankshaft moves forward, moving the pulley forward with it. When you release the clutch pedal, the crankshaft moves back again and the pulley comes into contact with the front motor mount. The noise that is caused by this will telegraph through the engine, clutch and transmission, making you think it's an internal problem.
To test, with the engine off and someone holding the clutch pedal down, place a piece of cardboard between the back of the pulley and the front motor mount. Start the engine with the clutch pedal still depressed. Watch the cardboard as the helper lets the clutch out. If the pulley shreds the cardboard, you have probably found the cause of the metallic buzzsaw noise.
Marshall