Alec is right about cold-setting the frame- I did mine from the 116 to 135 to accommodate an IGH I found cheap. It wasn't difficult and won't damage the frame if done carefully.
Also, the UN54 won't work without some modifications to the BB shell- it needs to be faced 3 mm from 76 mm width to 73 mm width- and either needs to be re-tapped to 24 TPI from 26 TPI, or the bottom bracket modified. I chose to modify the bottom bracket- three rows of 24 TPI threads will screw into a 26 TPI shell- so I ground off all but the outer 3 rows of threads on the bottom bracket and installed it normally. It has been working perfectly for the last year or so, no loosening or creaking.