I think the XXX0079 is suposed to be 9790079. Could be a bad casting or damaged or ground. Don't think it is a service replacement number.They did use the last number of the casting number for the date so you should have a 69 date code over by the distributor hole. A letter for the month, two digits for the day of the month and a 9 for the year.
What about the number on the front just above the pan? Not the 149568 block serial number with the XB code but the lower one just to the right of the timing cover above the pan, on the left looking from the front. Should be a couple of numbers a letter then six numbers., should be vertical not horizontal.