Any 7/8 inch bars will fit, usually taller bars are much nicer for trails I think, I use the Sunline AV-1 antivibration KX tall bars, better leverage, means easier turning.
Go narrow if you do a lot of woods riding or wide if you aren't worried about trees. You can fit ProTaper bars in the stock clamps with a set of spacer/risers that cost about 40.00. Otherwise, any 7/8 bar should fit. The only other measurement is how far apart the handlebar clamps are relative to the width of the mounting area of the bar. This is more of a streetbike issue than dirtbike, but it doesn't hurt to check.
First, turn the mounts around to open up the cockpit. You can buy high rise mounts if you want a lot of height. I just use MSR Dominator Mini Hi Rise Bars. Just the right width for woods and at least as tall as any stock bars. Also the price is right, about $35 from Rock Mtn last time I looked. John