Kris,

Your questions must be answered with more questions, as you fail to provide any context for the bike in question. You have an italian bike designed for racing - what is the intended use for your new build? How much are you willing to spend? And be warned that opinions on this matter will vary - some will argue that it's not the steel, it's the care spent in constructing the frame that counts.

In my opinion, a vintage bike that is intended for frequent riding is one that is manufactured with care, and built up with good-quality components that suit the bike's intended purpose. Type of steel is an important variable, but it is just that: one, of many, variables.

Back to your original question: here is a link to a chart that lists a variety of manufacturers' steel tubesets, their weights, maximum rider weights, wall thicknesses, and intended usages:

http://www.desperadocycles.com/Tubin...per_Tubing.htm

Reynolds, Ishiwata, Tange, Columbus, and True Temper all have good reputations for manufacturing high-quality steel tubesets (there are others, they just don't stick out in my mind right now), but again - a badly built-up bike made from the finest steel will still be a pain in the arse to ride, and end up sitting in the garage.

Good luck.