This past weekend I decided to convert my DA FH-7700 to an 8/9 speed and fit it into my 126mm dropouts on my Cannondale. About a year ago I removed the 9 speed titanium freehub body and installed a 7 speed freehub body from an M732 freehub. In the first post the freehub body on the left is the 7 speed from the M732 and the one on the right is the 9 speed from an M760. In the end it ended up at 127.2mm since I needed to place a spacer behind the cassette and needed a bit more chain clearance on the DS.
I added 2 shim washers totaling .8mm between the 7700 freehub and the M760 freehub body.
I built everything back up and the distance from the spoke flange to the end of the freehub body is about 1mm to 2mm less than the distance for a correct freehub body. The downside from using a shallow flange freehub body was the clearance from the spokes at the flange to the large cog. It was less than 1mm.
I temporarily installed a 7 speed 14-34 cassette with a 1.3mm spacer behind the cassette for more spoke clearance and everything shifts fine. One of my concerns was being able to move the FD cage inward enough to not get chain rub with the more inward large cog location, and not drop the chain. I'm going to try and install a 13-36 8 speed cassette with 8 speed shifters in the next week or so.
John