IMHO... keep the 600 crank set, swap chain rings to the sizes you want, and use friction style bar ends.

The 74/ 110 BCD pattern has the widest chain ring selection out there, so you should be able to find
ones that will give you the gears your wife needs. 28/40/50, or 34/42/52, perhaps? Stick with a 7 speed
freewheel to keep the cost down. As Bill said, bar cons are the way to go with that steed, and I bet you
can find some 7 speed indexed Shimano BS-50's and an older MTB R. DR that will do the job, like an older
STX or STX-RC. Or, just stay with friction, and use a set of SunTours.



EDIT: BG & Bill are correct... most triple road bikes from the period were ½ step + granny; either 28/45/50 or
28/44/50 if the bike was spec'd with BioPace chain rings.