I can't dispute the originality of the numbers, but the marking to the left of the VIN looks less like reflections, and more like feed lines from a deck milling pass. Most decking is done with a milling cutter, not a Blanchard grinder, so the carbide inserts or brazed cartridges leave a feed line (similar to the feed lines you see on distributors after they are turned). I get the suggestion that the decking continued over the numbers, but since it has been stoned or abraded the feed lines are either extremely light, or were worked off.
The VIN numbers are uneven, and cocked. I checked out one of my original blocks, never decked, and the VIN stamp on the pad is very even, and uniformly light end to end. It also nearly gets into the build stamp on the block. Mine are very light compared to the pics above, which doesn't really point to anything with the exception of hand stamping with a gang stamp, which is not always consistent person to person, or strike to strike. I'm pretty positive the build stamp on the pic is original - same font (the "6" in particular) as my known original.
Broach marks are end to end, as the block was stood up and broached parallel to the crank bore. Broaching usually leaves a light straight line, end to end on the deck, with no angular marks. Angles are generally the result of hand scraping or abrasives (sanding, wire brushing).
Just my opinion -