'69 Swinger-340; 4 speed

Here is what I can make out...

in raised lettering... 2B43675
on a plate .... 0612

Course the 'X' I mentioned...

and under the two numbers which is written on the paper in the picture below... I noticed an inch long piece of metal laying in the right side head. Partial piston ring?? hmmm actually it probably wouldnt' be that straight....