Casting number will be above/behind the starter. I'll bet it is a D2AE-CA. Same casting used for both 2-bolt and 4-bolt mains. Near that will be the block casting date. 2L13 would be Nov 13, 1972.
Next there will be a partial VIN at the back face of the block, just below the driver's side cylinder head on a machined-smooth pad. The numbers are not neatly stamped. In your case it will probably read 3F5xxxxx (x's are the sequential serial number)
Then there is there is the engine assembly date, ususally a week or two after the block casting date. That stamped number is on the front face of the block, just outside of the timing cover on the lower passenger side.