Well progress so far is an offer of part of my money back and I keep the guitar, so I'm working on it. It won't make me any profits but it might get me a playable old guitar after extensive repair that would be - well - you know - "nice" (albeit still with a badly bowed front).
Hagstrom Acoustics are quite rare, and rather collectable if not such big names as the usual. They were built for Hagstrom not by Hagstrom. A Google search and an hour or so following links makes an interesting read. Regrettably after Bjarnum went in the 80s there are no systematic records, and it has taken me a lot of internet rummaging to find out what I now know. The only ones I like are the J45s (very like the Gibson, but 15 frets to the body, not 14) and the 12-string equivalents sometimes called J45-12 and sometimes H-33. This one is a J45.The J45 comes in 3 versions plus the electrified equivalents designated J45E.
Tailpiece version - I think all ladder framed. One in Hobgoblin Nottingham at GBP550 sticker price right now. Serial number 6 digits starting with a 1. Year possibly 1976. I don't like tailpiece guitars. They don't sound "right" to me. I put it down to the absence of twist in the top. I once saw a heavily repaired tailpiece one in the shop of Andy Perkind (the UK Banjo maker). Did not sound right - no shimmer to the sound - but that might have been the repairs.
X-braced version - but A-braced in the minor bout. My wife has one. It is very well thought of by all who play it. It is insured for quite a lot. I have seen one other and it was in Andy's in Denmark Street in London at GBP400 in 1988, even minus the sidecappings on the neck and re-fretted. I'm told 6 came to the UK in late '62 or early '63. Serial number 5 digits starting with a 5. Current market price (original and first class) - about £300 less than what this one would have cost me if I got all the reapirs doen to bring it to that condition. "Worth" more, but the law of supply and demand is what it is. Hagstrom UK pages tell me that the x-braced mostly went to the USA. If you see a good one, and if you liked the round Levin Goliath sound, rather than the modern twangy sound, get it fast, in my opinion.
The Ladder braced one. I did not know these existed. That's what this is. I don't like the ladder-braced sound. I played an old Gibson ladder-braced dreadnought in Macari's in London the other day adn did not like it at all. But Hagstrom UK say that this is the one most favoured by players. Surprising, since ladder bracing is not a clever structure for resisting twist (compare the torsional stiffness of the Shelby Cobra with the Birdcage Maserati and you'll get my drift). Mostly as a result the tops sound dead and thuddy. Like the official Robert Johnson Gibson small-body. Probably good for blues if you can play delta properly. My guess is the market price here, if original and good would be about half what it would cost me to get this one to that state.