Remember that the XS1100 is a shaft drive bike - so a hard tail kit would be MUCH more complex than a kit for a chain drive bike. Also, the XS1100 is a (roughly) 600+ lb motorcycle capable of nearly 130 MPH.
...having said all of that, I simply must ask - WHY, on earth, would anyone want to hardtail an XS1100?
Fred - anything from you on this one?
Pete