Thanks for the info, Harley !! Yeah, based on
the slides, I'm leaning more towards the HighStandard too.
The full-length vent rib and squarish forestock, with the
adjustable (Full/Mod/Imp.Cyl) choke stuck on the end kind
of set it apart. Makes it look kinda like a heavy barrel
varmint gun ! Funny, though, although it's got such a
looong barrel, mag cap is only 4. It takes 3" shells too.
For your edification, most of the parts on the schematic/
parts list are numbered "207xx". Other than that, I would
consider this a solved case. Thanks again.
PS I probably won't go thru the trouble of barrel shortening,
even with a smith, it just seems so unwieldy with a 27 incher.