Went to do headgaskets and found more..

[Taylorb26]

This is what the head and block looked like on the passenger side 4 & 6 cylinder edge. This whole engine was new, lifters and cam had almost no wear at all, pistons looked new and we're .30 over. Just don't know how this slipped past the previous builder

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[Gramps]

It happens. Same thing same spot on my father in law’s truck, which is what sparked the total overhaul and restoration of the truck.
My guess is that it had either happened after assembly, or an inexperienced person assembled it. Don’t know any machinists that would have let that leave their shop, but there are bad ones out there.