It makes no sense to think that the engine will overheat when the vast majority of bigblocks produced didn't have the holes and didn't overheat.

To the OP: I wouldn't take the engine apart just because there was a little water in a cylinder, as long as you know how it got there.
I don't know of any bigblocks that left the factory without steel shim head gaskets. At least any wedges, having never been within ten miles of a Hemi teardown.
So IF you do take the engine apart the steel shim is what I'd suggest. IF the block and the head both have the extra coolant passages, it should be pretty easy to make corresponding holes in the head gasket. You'd also have the old gasket to use as a pattern.
I've never heard of a bronze head gasket. Ever. Steel does rust and form a reddish oxide which could be what you're seeing. I can't imagine someone putting copper head gaskets in a motorhome.
IF you pull the intake manifold and see original gaskets, there's little chance the head gaskets have been changed.

Good Luck!
R.

PS: You are overthinking this situation. Try not to worry so much. Remember, Mopar means never say never!