I have a correction on that block stamp...#2468130•12
And near that number is what may be the production m-d-y=6 20 68
That’s the casting number. The first 8 digits are the part number, the 12 is the number of times the casting was revised. The 6-20-68 is the casting date of the block. It’s totally possible that the block can be cast that far in advance of your cars assembly date.
on a flat of about 3” long, right above the oil pan rail in the passenger side, is the place where they stamped 69 and later motors. The VIN, or partial VIN should be stamped there, with at least the character size, date digit and the last 6 digits of the VIN the motor was destined for. This should match your body numbers and dash VIN.
there is also either a raised pad on the drivers side too, right in front of the valley pan for 413/426/440, or a machined of behind the distributor on 361/383/400. On that pad will have the digit date, the displacement, the assembly date, and could have other characters there as well to signify assembly corrections or HP blocks.