With a little tinkering you can make a fixture from angle iron and a carpenter's level to get an accurate measurement of how far the #1 connecting rod drops below the oil pan rail, and then use that dimension to see if the pan is deep enough to prevent the rod from hitting it. You've already checked for all the usual causes of a noise- - - -now it's time to put some effort into finding the oddball ones.
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!