As Salmon said above the EUN on your block will match up with the EUN on your PHS report if it all original. It is the 6 digit number above the 2 letter code on the front left side of the block as in this pic. Also the original rear end 2 letter code will be stamped on the back side of the drivers side axle tube. A little sanding or buffing should find it. The codes are on this site along with other '67 codes you can track down.
