I agree with Gary. It kinda looks like slivers to me. Is the dist drive looking ok, or maybe wire brush wires from cleaning out lifter bores, or a few pulled threads from some bolt, or pieces from a bottom end tap. The engine looks like it was built tight to me. Cam bearing slivers . How are the mains? Rods knock but still has some pressure, main bearings will take away pressure quicker.
I agree with Al about the wire wheel wires. I don't think that anything else inside the engine would leave that distinctive markings. Typical shavings would have about the same material strength than the oil pump parts and so they wouldn't leave that clear markings. Someone did a sloppy job when cleaning out the oil passages, lifter bores or something else. I used nylon bottle wash scrubs to clean out the inside of the engine.
