I'd have them confirm that mileage. "99,999" looks like they just hit some numbers to fill in the blank cuz the odometer wasn't available, either because the screen was out or someone pulled the cluster before they recorded it or who knows.
If it were me and I could get a confirmed low-mileage, unmolested factory-sealed motor for ~$1,000, I'd go that route before spending 3x that on a rebuilt from an engine mill. I know there are reputable rebuilders, but I still get the feeling that since they only need to warranty it for X miles or X time, they have looser tolerances than the factory. Generally, one from the factory is designed to provide 200K miles of service, but many eclipse this by far with minimal repairs. I'd have to tour an "engine mill" to see their operations first-hand to change my opinion, which I'm totally open to doing.
I wish you were closer. We'd swap that motor in a weekend. Just bring a few pork rolls.