Big Block ID

That's really not the number you need. What you're looking for is a STAMPED number behind the timing cover in top of the block JUST in front of where the intake valley is.....kinda on the exposed part of the china wall. Here's an example of what it "might be".
Something like this. C541-8-1001 That kinda thing is what you're lookin for.,
Rusty, does it matter that it has the extra water holes. From the looks of it it appears to have 2 sets of water pump water ways/holes in the front of the block?
Thanks again for all the info