The OAL is 19 and 11/16 inches. I do not know what the LB-74 and LB-76 refer to so I am not familiar with those references but I take your word for it. As for the bent quillion and muzzle ring, both of those are now fixed. This is the other stamp that I have questions on: Attachment 116077
A European collectors forum puts the markings as possibly coming from Wakeda University which apparently was part of the schooling program for the Japanese and dates the bayonet to sometime prior to WW1. This would indicate that it was not part of a foreign military sale program.
My apologies. The WU is said to be Waseda University, not Wakeda University....