Thanks, Folks.
I read through The Art Of Building The Pennsylvania Long Rifle and learned just enough about the so called "Schimmels" to be willing to get some of my exercise by jumping to conclusions.
Every vendor I spoke with is bound to long delays in getting a swamped barrel, so sending it back is not on the radar.
In this and that "Other" Forum all the comments are pretty helpful.
I just sold a Pedersoli Jager Hunter I gussied up on Gunbroker where it seemed heavy and awkward until I shouldered it. Then it got real steady.
SO...keeping that in mind, here's how this is gonna go.
I'll shoulder it when it gets here to decide.
I might just pack it up and drive down to Bobby Hoyt (We are likely to move back to PA later in the spring) and have him take it from .58 to .60 because it is a one inch bbl., 31 - 35 inches.
Since I am at the bottom of the pyramid in terms of experience, I am willing to gamble a little if that don't work or he advises against it, so I'll ask him. He did some work on a previous octagon to round for me and this guy is really good at what he does, so I will rent his eyeballs for a few minutes.
If I get to filing after a couple of Hail Mary's and a St. Joseph The Worker Prayer, then the plan is to work the corners so that the filed width of each corner works up to 1/8 the width of the flat evenly all the way down the barrel. Then I heft it and see how it feels.
If it feels OK then I still have the inletted stock to work with and can bed the barrel if I want to compensate for the two corner gaps in the channel.
Of course, I am gonna have to ask how they bedded barrels back then because Fiberglass sorta turns my nose into an allergy factory.
I might even get brassy ( or foolish) enough to swamp the corners a little. I'll burn that bridge when I cross it.
Before I attempt that, I have to remind me not to take myself too seriously. Knowing what I know and don't know about the 18th Century and its crafts, when a real expert looks at the gun and cringes, I can come back with something like..."This is one of those conjectural, work-a-day guns that would have been low priced and used until it did not survive to make it to Dixon's Gun Fair"...
If he is kind enough, I might offer him a discount on one of my pairs of shoes. If he is mean enough, then I will over charge his wife for a pair of blue kickers with red bows and heels.
In either case, if I ever run into any of you at an event, be sure to remind me that "I told you so" and coffee will be on me....