Originally Posted by
jake8
Swif if you go to a new wheelset and make it modern it will be 130mm spacing, but your bike is 126mm so you will have to stretch your rear triangle or cold set it.
From this link at
http://www.sheldonbrown.com/frame-spacing.html ...
you can safely go up one size in spacing this way, just springing the frame apart. I can't give you an absolute guarantee that this won't cause damage, but the odds are very much in your favor.
Piece of cake on my '84 Miyata. Originally 126mm. Now with 132mm wheel. No issues mounting and dismounting the wheel.