thats what it is, but the action is scaled down for the smaller cartridges
this sweet little rifles were made in Suhl/Zella mehlis for the trade by small firms. most times no maker marks they may have the name of retailer or wholesailer like Stukenbrock. the proof marks can show if actually made in Suhl or in Zella Mehlis. I believe this different gunmakers have got the actions in the white from one or two specialised firms in this area like they bought the barrels or triggers. I would remove the rust by polishing the action with steel wool and paraffine oil. to bad the original scope is lost but you can find period scopes on egun or ebay and probably also a gunmaker who is able to fit it into the old claw mount.
the 6,5x27R is realy rare so I suspect the 6,5x48R or 6,5x58R what gives you a fine roe deer rifle.

brass can be made by using the 9,3x72R case or 30-30 Winchester