340 cylinder honing question

Unless the motor was sealed in plastic, with the rocker shafts loosened/removed, so the valves are all closed, - the motor will breathe.
Thru open valves, the daily heating/cooling, the humidity, will actually suck in and expel air.
The cylinders open to atmosphere often have a rusty area on the cylinder walls.
We had an example here not long ago, engine sat x yrs, upon disassembly coupla cyls rusted badly .
I've seen it a few times personally, particularly marine engines, with wet exhausts.
Borescope each cyl if big $$$ involved.
Good luck. I'll try to find link to pic.