"I suppose this has been beaten to death some time before my arrival, but I am looking at a Masi frame that is already refinished beautifully and I'm thinking " I could re-do the spacing from 126mm to 130 and put new record stuff on this and I'd really have a sweet bike"."
Isn't this what the modern framebuilders on this list do everyday? R. Sachs, Baylis, me included take what we feel to be the best manufacturing techniques, stir in a little modern wonder tubing, a pinch of modern slick shifting components and make exactly what you are talking about. A wonderful riding bike that could be raced, even at the highest levels but doesn't feel like riding a big piece of drift wood.
Dave Bohm
Bohemian Bicycles