Should have a casting # of 2468330 if it came out of a cuda or challenger. May be the same for others. Part # for the 68 charger Hemi was 2951623. This was the # for the short block.
The engine id # on the Hemi is at the rear of the block on the passenger side near the oil pan flange. There should be 13 numbers and the go loike this.
First one or two letters will be the plant code where made.
Next 3 diget= cubic in displacement.
Next 4 diget= represents the 10,000 day calender
Last 4 diget= these are the daily sequential number of engines built
If the letter "S" or the letters "HP" follow the displacement code, this denotes a high performance block. The letter "H" shows it is a Hemi block.
Hope this is some help. Good luck If you don't want it put me in line.