You're okay. The TW kick boss (the splined part that slides onto the kickstarter shaft) does not slide all the way onto the shaft.
Remember that collar that you removed when you installed the new idler gear? Sometimes I just slide that onto the kickstarter shaft before mounting the kick lever/boss. This adds a tiny bit of unnecessary weight, but it is handy if you ever wanted to remove the kickstarter and return the engine to stock.