Your rear hub is definitely spaced at 126mm, while modern road frames have 130mm rear spacing. So not only can you not put a full 9 speed cassette on it, you can't use it with a newer frame unless you add some axle spacers/washers (OK, maybe you could get away with squeezing a steel frame around it, but don't try forcing a 130mm aluminum or carbon frame to hold a 126 hub). More info on using more than 7 gears on that hub: http://sheldonbrown.com/k7.html#bodycompat

BTW, it's nice to hear others confidently predict that a 7s tricolor 600 RD could handle the extra ~5mm lateral width of a 9s cluster (http://sheldonbrown.com/cribsheet-spacing.html) -- maybe I should rethink my planned IG-to-HG upgrade for my earlier 600 rear hub, though I'd hate to set aside those great old 600 downtube shifters.