Well Ken, looks like you may be on the right track at last. RTV is great stuff used properly. I’ve seen it in fuel lines, water outlets jamming thermostats and almost ever where you can imagine...... Sounds like the crank has been getting oil all along so the bottom end should be good to go. Although, I think I would still pull a cam cap or two just to cover all the bases! One last thing.....did you discuss any compensation with your builder? You got a good three or four days labor, and a few $$$$ going on here. I think I would squeak a little and see if he “lubes” you any!
    Good news is at this point it sure could have been worse. Even so that stuff is tough. I don’t know of anything you would want to pore in the hole to dissolve it, so it will be hard to clean that hole manually, and any debris will fall down in the “Oil passage”. Keep us in the loop! May be time to ask for another engine and some $$$$! For sure the builder is going to be reluctant to warranty any future problems, because you worker on it.

Skipper