Welcome to AO.
That's a nice car you've got, but I've got a question for you. What do you mean by "matching numbers?"
I'm not trying to be critical, but I've never heard the term applied to Alfas before -- if anything, from what I've learned about Alfa production "matching numbers" is anithetical to Alfa Romeo production.
I know there are probably two numbers on the car -- one on the body and one on the engine (or in the engine bay) -- so I'm guessing that's what you mean, or are you referring to something else?
I know that "matching numbers" is a really trendy restoration term, but I also know (at least in this part of the world) it has no real bearing outside the antique Corvette world, even though it gets applied to every make and model out there, whether it is physically possible for them to have matching numbers or not (and in most cases, it's usually "not").
Corvettes were noted for having all their parts stamped and dated -- everything from glass to engine components. When Corvette people refer to matching numbers, they mean all a car's components match -- not just the body and the main engine block. Alfa seems to take a "whatever is in the parts bin today" approach to building its cars, much to the chagrin of people trying to restore these things later in their lives.
More on matching numbers (for those who care
"Almost every mechanical part made for a Corvette has a date code, either cast or stamped into it. These simply identify when the part was made. To the factory, this date probably made sure that they didn't leave any stock laying on the shelf too long, although if you have ever watched any factory production line run, it is doubtful if anyone ever reads the dates. The purpose of the date to Chevrolet was probably to ensure a means to track any defects should they arise. If a part dated March 3 and one dated March 21 were both defective, attention could be paid to those parts built between those dates for other possible defects.
"Today, these are used to determine if the part is correct for that Corvette, as an engine with a date code of D 16 5 (April 16, 1965) could not be correct for a '63 Corvette as the engine was made after the car was made. Parts too early are usually not correct either, as they would have been installed on an earlier vehicle, such as a B 23 3 (Feb. 23, 1963) in a '67 Corvette. NCRS provides a window of 6 months on date codes prior to the build date of the car. Obviously, a part on a car could not have been made AFTER the car was made. (See Exceptions.) But given how new items were constantly loaded on shelves, with existing items being shoved further back each time, a part could sit for many months before being assembled on a car. Usually, the parts were used within a few days or weeks but there are many documented original cars that have parts several months old.
"Be sure to notice that some parts have both a casting and a stamped date code. These can be several days apart. The stamped date code is when the part was assembled and should be the one considered."