the old 420 and 430 are significant as being one of the very few examples of an o/u actually made in America. those 2, the marlin 90, the remington 32, now the galazan. and i've forgotten what it was but i stumbled across something else even more arcane than the old savages a while back but can't recall the manufacturer.
and the savage o/u rifle/shotgun combo guns and the 410 built on that frame. those would count.
i had the 430 and a marlin 90 at the same time. the latter with 26" bbls and the former with 28's. the marlin was heavier than the mfg spec and the savage was lighter. in spite of 2" more bbls and much more dense (and attractive) wood it was only 6oz heavier. both fit equally well and i shot them equally well. i've owned guns far more expensive than either that were no where near as usable.
i had a 333 (valmet) 20 ga and it was an outstanding gun altho needed more LOP and had a little too much drop. never did own one of the 440 series. i think their production span was a lot shorter and aren't near as common as the 330 guns.
and yes, the valmet guns are unmistakably marked as to origin. don't recall the exact markings but you can't mistake them. our cabelas has had one in 12 ga for quite some time and is identical to the savage guns in every respect down to the stamped checkering pattern and rolled on engraving but it carries no Savage markings whatsoever. they're not really out of line on the price. i think people just don't know what it is.
roger