Nice build!
Makes me a bit nostalgic for this one (passed along about 5 years ago):
I like the Colnago-branded crank dust covers. Never seen those before; the bit of yellow I can make out is probably just the color of the plastic showing through rubbed-off chrome plating. And I think it may be a '79 because your BB shell has the older clover cutout, top-of-shell guides, and doesn't have one of those foil chainstay decals that were used for about a year. A Bicycling magazine from summer of 1980 called out the chrome chainstay decal on their test bike.
What are your riding impressions on the fatter rubber? Never had anything bigger than 19s on mine.
As far as modding the rear DOs, please don't follow that advice. After all, one only needs to deflate the tire to remove the rear wheel for maintenance and flats - and in one of those cases the tire's gonna be flat anyways
Enjoy!
DD