Hello and welcome to the forum!
The Block Casting Number you posted, 3970044 is not a very common casting!
The 3970044 block casting was a short run casting (low volume) through the Tonawanda engine plant and was not to well documented.
So, it's tough to come up with exact information on it, as this Casting Number does not turn up.
If you would look on the Passengers side, front of the engine block, just below where the head mounts to the block, there should be a raised pad that will have to rows of numbers hand stamped on it.
Please clean that pad well and record the numbers (due to paint, dirt, grease build up, they may be hard to read) and post the numbers in this thread.
From those numbers I should be able to find the information you requested.