There might be an oil slinger inside the cover that can rattle around once the damper is removed. Does the wear mark correspond to the position of the sealing lip of the seal in the timing cover? If so, a "speedy-sleeve" for a small block V8 is the same size as the stovebolt damper hub, (1 3/4" OD) and it's stainless steel- - - -much more wear resistant than the soft steel hub snout. I'd suggest dropping the pan and pulling the timing cover just to do a good job of inspecting the timing gears, etc.
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!