Scott,
I used an identical block for my garden block build that's outlined her in the projects section. It doesn't have the 428 deck water passages either but it came straight out of a 67 wagon, had all 428 internals, and looked to have never been out of the car so I have to believe it indeed was used for a 428 block, maybe the factory used what they had that day I dk, I do know that even after going .010 over to a 4.140 it still had good sonic #s. The block is nothing special, not a 3 web block but the thick cylinders it had was a better option to me than a few other 105 blocks I had at the time.