Here is what I have found on it.
Casting date I think is 5/28/68
Casting number is 2780930-340-3
Stamped under head is EW340P 8840260 there may be a 2 after the P not sure
stamped on pan rail 9B431163
the 1 6 and 3 are just guesses.
I am not really looking to sell and engine as much as I am looking to buy a car.