Read the thread posted by BG, you will see many of us have used a variety of speeds and component groups on vintage frames. Myself, the move from 6/7 speed (126mm) to 8/9/10 speed (130mm) does not require a coldset. You are talking just 2mm per side. I have put various Shimano 8/9 speed STI groups on several bikes that came with 126mm spacing. I'm working on another one right now.

Its really about your budget, and what you find. Rarely have I singled out a particular group, instead, I have remained flexible and ended up with what I have found. Flexibility = lower cost.