Some quick thoughts (and looking forward to input from others):

My impression is that the internal routing began in 1985. There seems to be at least a year or two of overlap when both top-tube and internal rear brake routing was used, and then it seems to be all internal going forward.

I've seen examples that have the signs of being 1982 or later, but which lack the FD braze-on tab. I think it became standard on the Tommasini road bikes at some point in the 1980s, but like many build details, there seemed to be an overlap between years where the bikes were built with and without the braze-on. It may have been something that the buyer had the option to declining.

I think your's is the only one I've seen with the 'Racing' decal on the top tube. My impression is that in the early 1980s they started labeling road bikes 'Prestige' and 'Super Prestige', with the decal always on the right front top tube. Prior to that the standard road model seems to be 'Racing' with the decal on the right chain stay. The 'Racing' versions with the chainstay decal have no 'Tommasini' decal on the seat tube. With the introduction of Prestige/Super Prestige decals, we also see the 'Tommasini' in stacked lettering on the seat tube. I'm guessing yours is from a transitional period, right around 1984ish.

I've never seen the 'Professional' decal that I recall. The Tommasini decals seem rather robust, and the fact that this decal is literally going to pieces suggests to me it was added later. Maybe the bike was meant for a racer, and slapped on later?

The AIR fork you have is what I consider the 'later' type fork. You see a more flat top fork with a raised gear surrounding a sunken 'T' and a dash-dot-dash pattern on the fork crown in the late '70s into around '82 and maybe '83. From '84 or '85 on they all seem to be AIR forks like yours. There there is a second type, as on my bike, that loses the raised gear logo and the dash-dot-dash, but which is more aerodynamic. It seems to be a transitional fork design, and I see it on bikes I identify as being in the 1982-1984 period.

Your bike looks like the next size up from mine, so I'm not surprised your seat tube seems to be SP.

What are the letters stamped on your BB? It looks like '52' and 'B5' but I can't quite tell.

Beautiful bike!