Tools-N-Gizmos has used and some new old stock Kwik 200 stuff. Also, the RS200 taper sold by Travers is supposed to be a direct drop in on Kwik 200 spindles.
Largest I have seen is 1" for Kwik or RS, but a work around is to rigidly mount a boring bar vertically to your table. A screwless vise with a vertical slot should be adequate. Remove the set screw from a 1" solid end mill holder, and then remove a little at a time by passing it up and down over the boring bar until you have an exact fit for a 1.25". Reinsert the set screw, and then install your 1.25" shaft tool. I'ld only do that if you feel you have enough meat for it though. Then stand on the other side of the shop behind your truck when you fire it up and run it. LOL.
Bob La Londe
http://www.YumaBassMan.com