one simple check that can be made to give some indication of tubing quality the diameter of the bicycle's seat post. for conventionally constructed adult steel frames the typical range here is 25.0mm to 27.2mm. in general, the larger the seat post size the better the quality of the tubing (somewhat of an oversimplification).

here is a directory which gives some information about the sizes:

Sheldon Brown's Seatpost Size Database

to see other bicycles with your type of seat stay treatment you can check google images for the brands kalkhoff and victoria.

here is a forum thread on a bianchi bicycle constructed with the same agrati bulge-formed head as is seen on your frame. scroll down to message nr. four to see a closeup picture:

http://www.bikeforums.net/classic-vi...lp-please.html

best wishes with your investigations!