Metal in the oil is very bad news, especially on a fresh rebuild. I'd suggest a complete teardown to a bare block, find the source of the metallic contamination, and build it back up from scratch. The missing/broken bolts tell me all I need to know about the original builder- - - -stay FAR away from that guy!
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!