The OP might want to go to Bob Hovey's Masi website to put his bike into better context. My contribution to this thread was let the OP know that an early Masi made before 1970 was a very rare thing to have in the US. Much rarer here than to have the same or similar one in Europe. How that relates to its monetary value is something I don't know because I don't pay much attention to vintage bike/frame sales. For someone that is a Masi enthusiast, this would be an exciting find. How much they would be willing to pay for it if it is their size is another question. It is in poor but rideable shape. It would be nice if it went into a collector or enthusiast's hands. These kind of bikes can show the progression of bicycle development over time. Particularly of a top classic Italian builder like Faliero Masi. Sometimes collectors like to take out old bikes of a certain era to compare how they ride to one of a different era.
10 speed bikes of any sort (like the most common versions, the Schwinn Varsity, Continental, Super Sport or Paramount) were seldom seen anywhere in the US before 1970. They would be found mostly in California or the big cities. My cousin and I did a bike trip in Vermont in 1966 on Schwinn Super Sports and everyone thought we were just crazy college kids out for an adventure. When I was teaching English in Japan during the 1970/71 school year I was shocked to read an article in Time or Newsweek titled "America discovers the 10 speed bicycle". I couldn't believe it and when I got back to the States the summer of 1971, I was amazed to discover sales of 10 speeds had exploded and my friends that knew I was into bikes were asking me all kinds of questions. In the midwest anyway the change from adults having no interest in 10 speed bikes before 1970 to lots of interest in 1971 was dramatic .
The good news about making this frame a rider is that it was designed for center pull brakes. This provides more tire clearance for today's wish to ride with fatter tires. Racing bikes of this era were all designed to use tubular tires without exception. I'm betting that at some point - either when the original owner bought the bike or had them changed out later - he had the rims (these are steel?) to 27 1 1/4". 700c clincher rims (the same ø as tubular rims) were not available until around 1976.
I'm pretty sure that if the crank is original to the age of the frame, those cranks will have a bolt hole diameter of 151. That means the lowest inner cog can only be 44. I see in the pictures that the big ring is a 49. If someone is riding by themselves a 49 makes more sense than a much more common 52. Only when the rider's speed gets over 20 mph is the bigger chainring useful.