Have you checked the crankshaft pulley bolts for looseness? That noise is way too fast and erratic to be camshaft-related. The cam runs at half crankshaft speed. I bought a Corvair once for pennies on the dollar when it had loose rivets holding the crank pulley onto the damper. The noise sounded just like a rod knock. I had a welding shop tack the pulley to the loose rivets, drove the car for six months, and sold it for four times what it cost me.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!