dude, sounds to me like your detent isn't installed properly.
if you didn't tighten the mounting bolt, it could explain why the star won't go into position....
have you ran her through all the gears? you're sure that she WILL go into all the gears at speed?
i doubt it's the shift forks. sometimes shift forks get bent real bad from slamming through the gears, but the #1 symptom is the tranny will come out of gear in motion, which it doesn't sound like is your prob.
also, it's possible that you just have your shift lever set too low. the shift lever needs to be able to return to it's rest position between every shift before it'll let you shift again. i've run into this prob on my street bike a lot when i buy a new pair of boots they'll have a lot more sole material than my old ones which are all raggedy. so i won't be able to fit the boot under the shifter as easily and it'll interfere w/ the shifter's return action.
does she shift through all the gears if you use your hand instead of your foot (like w/ the ass end jacked up).