if you do the calculations, .050" on the outside of the flywheel is not really much (I hope I am understanding your situation correctly). Math: (.050/(diam of flywhwl at mark x pi)) x 360 = degrees difference in timing. You will probably come out at around two degrees, which I think would be barely noticeable. When playing with timing, it's a good idea to use at least part race fuel. I'm not a big fan of minor, gradual changes...you can't ever feel what the bike is really doing. Move it a ways, try it, move it back the other way, etc.
If it's too far advanced you should be able to hear it pinging or see it on the plug. Running it a short time this way shouldn't hurt it, unless you are WAY advanced.
If you haven't lost your overrev yet, chances are it isn't too far advanced.