Thanks a lot to both of you guys.
Jeff, glad to know the date of manufacture; it's actually held up pretty well for a gun that old. Top lvr still a tad to the right, all screw heads aligned, blueing ~93%, stock in good shape with no oil infiltration at the head and W to M fit pretty decent actually. The chambers have indeed been lengthened and you're right, it would seem really unusual for an importer to bring in a 2.5" twenty gauge low end gun during that time when the only shells available to the average hunter were 2.75" or 3".
ChiefShotguns, You're correct re: this being toward the low end but it doesn't seem quite as crude as you've described. It weighed in at just over 6 lbs and has a fairly lightly built frame and barrels. In fact, I was surprised to find the chamber walls to be as thin as they are. The bbls have a few minor file marks remaining at the breech end but lots of them under the forearm. Surprisingly the blueing and engraving on the rcvr is fairly good--engraving is very similar in pattern and quality to a Brwng BSS. And the trigger pulls are passable. So the quality might be a bit better than the ones you've mentioned but it it still isn't going to be showing up at the Vintagers.
But for whatever reason, I can actually shoot this gun pretty well on the skeet fld, by my middling standards at least.
Anyway, I really appreciate the help, fellas. Thanks a lot!