http://www.velo-retro.com/list.html

Velo-retro has a large selection of repro catalogs, although the earliest Cinelli catalog is a 60's one and may not have the exact info you are looking for. The Ron Kitching catalog from 1955 may be good as they were a Cinelli dealer although, again this one may just have parts and not bikes, the later 60's one does have bikes. You can email Chuck Schmidt the owner and ask him if there is a Mod. B in the early catalogs.

Here is a link to the Velo-Stuff site that has a lot of great galleries, including a Cinelli Mod. B
You can see that his "B" has the same lugs with "ears" as yours but it has the flat crown already.
http://www.velostuf.com/1950%27sCinelliModelB.htm

thirst