What exactly does it have on the bb shell? Any letter like "M" , "A", "V", "AV", "B" and then a size(in this case likely to be 61 or 62) just below the cutout in the down tube socket. Is the cutout in the socket a long oval, or is it sort of triangular in shape? GC's from Italy rarely have the drilled hiles in the extended seat lug point. That was one of Marios' features if the frame is Italian. If there is no MCXX on the BB and a serial number, then it's probably an Italian Masi; possibly built by Mario. I have seen (and repainted) two this past year and know of another. This one could be a fourth. Look for any letter or size on the bb DT socket.
Also the GC you have that you say does have a triangle cutout on the back of the seat lug is later than 1974. More like late '75 or later.
If there are no numbers or size on the BB then there is also the possibility of a down tube replacement which may have been the cause of the repaint. It is possible for the numbers in that area to disappear during a (careless or inexperienced) repair job. As always, if I saw the frame in person, I could tell a lot more.
> I have a repainted MASI 24" c-t. It has added braze ons brake guides. It
> does not have a serial # or an MCXX on the BB. It also has a seatlug
> without a window in the top tube tang like my 1974 GC though the seatlug
> does have the drilled extended seat tube tang. Can anyone help me with the
> history. BrIAN CHIlly in Berkeley (The other Brian B)