I say just start the swap! I did a 2003 fork onto a 79 special and it was a peice of cake. I used the stem and tree's from the gsxr I also used the stronger hollow gsxr axle with the stock xs wheel. All you have to do is trim the lower neck and a bearing swap trim the jam nuts and your done . Brakes were a nightmere, stock rotors are to small I would have a custom rotor made if I do it again. I redrilled and older rotor 92 gsxr with a huge offset to fit the xs bolt pattern It worked but it was kinda hack. I'll try to load a photo but there are some under pic. section here under cafe without a plan I think
Good Luck