Pieces of steel in cylinder??

Do you all think its bearing material?
That crank journal should be destroyed if that was the case.imo
Who put it together, that is the question I wanna know. Measure the crank and see if the bearings are even matched.
Muat'a been a loose std someone put a .010 under bearing into to do this kinda damage .

"Motor ran great till one day"

Fishy AF. Imo

"Whatever it is" is very obviously way softer than the crank.......and oh happy day! The crank looks salvageable, IMO. As @krazykuda Karl said though, you should remove every stinkin pipe plug and freeze plug, core plug, whatever from EVERYWHERE. Even and especially the one under the distributor and the one under the rear main cap. ALL OF THEM! Failure to do so will probably almost guarantee you leave something behind.