The cracks are marks from the steel mold the part was made in. The mold had some heat cracks in it. Its normal and wont hurt anything.

The wear marks are from the timing chain being loose. As long as it did not break through to water your fine. If its just a bit of the bolt showing its unlikely to leak.

Make sure your new motor has a rubber washer behing the tensioner for the timing chain.

Kevin

87 Turbo Intercooled Raider, roller cam, torsen rear diff, LSD front diff, lockup auto with modified converter, V6 brakes, low transfer case gears...