If new glass beads (not glass abrasive) are used at lower pressure, they peen the surface which improves the metal and does not leave bits behind. I use 45 psi. Using old or the wrong media or using too much pressure could do just as you fear.Some polish it out smooth and then bead blast. Im leary of bead blasting as there may be some bits still in the metal waiting to
come out and start circulating in the oil.
Fear mongering Im sure but....
"Shot peening" means peening with Glass Beads, Ceramic Balls, Round Metal Ball, etc. Glass Bead is most commonly used for crankshafts and connecting rods.Not sure why anyone would bead blast this - if you are thinking shot peening - that's a whole different thing, and a good idea.
That looks to me, like some where along the line, it was subjected to a wire wheel on a bench grinder.
My money is on that damage being caused by spending years rattling around in someone’s parts box...
But even a factory engine was made from stored parts, and if stored incorrectly. Either that or something was bouncing around inside the cases. Either way its needs rubbing down and polishing.