Hi, I'm an amateur guitar builder in Hokkaido,Japan.
This is my suggestion that replace of the neck to Fender 25.5 scale is necessary to move the bridge according to new scale. And also it is better to image total balance.
1) I have 1963's Duo-Sonic. In 2005, I have exchanged original neck to Tele's 25.5 scale neck. Bolt-on was OK, however the distance between 12F to bridge saddle was not enough.

http://www.okadadenko.com/cg/cguitar_duosonic.htm
2) I didn't like any modification on original Duo-Sonic, so I made Duo-Sonic copy body in 2007 and joint the neck then found new bridge position. That was not bad if one point was excluded. What was bad? Length from machine head top to body bottom was too long. It could not be enclosed in ordinary hard case.
http://www.okadadenko.com/cg/hbg_woodsmiles.htm
3) To short the total length I had cut the bottom of the body. However, it looked stupid a little.
http://www.okadadenko.com/cg/hbg_tele-duo2.htm
4) Then I refine the body then mount original Duo-Sonic pick-guard assembly.

http://sites.google.com/site/homebrewguitarah/halfmiles/planning-ds
https://sites.google.com/site/homebrewguitarah/parts/halfmiles-ds-with-duo-sonic-pu-assembly
This is my 25.5 inch conversion story. Sorry for loooong speaking.