Gents,
I am really very sorry for not having responded to your inquiry sooner, but I honestly haven't been on the Forum ever since I got rid of the Bullet.
So, I did indeed fit the 3.5 K70 on my B5 and it LOOKED AWESOME! It was a tight fit under the full fender of the B5, but it did indeed fit. Lots of riders loved the look and commented on it. However, the bike seemed a bit more "floaty" and handling was hampered in the sense that it wasn't able to fall into corners nearly as easily as before. High speed cornering was much stiffer and required more effort. Also, low speed handling was definitely hampered. Now, this of course is a question for the individual. Do I go for looks over performance? It depends upon the riding you do. Are you carving canyons? If yes, then I wouldn't advise it.
I originally did this in an attempt to to steady the ride on freeway rain grooves, but it did nothing to mellow the wobbles. I loved m B5, but the harmonic speed wobbles that I encountered on rain grooves ultimately sealed the bike's fate.
Last summer I traded her in on a 2013 Crystal White Triumph Bonneville. In all honesty, I haven't looked back. The Bonnie is rock steady on rain grooves, confidence inspiring in the mountains and very capable for long haul touring. Recently I added some performance pipes and a remap of the EFI so the bike runs and sounds like true Bonnie. To each his own.
I wish you all the best,
Boots