Very nice...
I didnt read if the original proof marks are present under the forend? I agree, Henrys name and address would have been engraved on the top of the barrel, this is a BEST quality rifle.
Your Bbl photo does appear to have the Nocks form - although one side looks milled off.
I have a 450 TD with this configuration as well as a 360 with a slightly different TD connection.
IMO - if youre going to restore, bring it back like Henry made it..
Thanks for sharing.