2002 yz250f head question

I have a friend that has a 2002 250yzf. It basically has sat in a box of parts for 10 years. They stripped the cam cage bolts out of the head. Buddy found a head from a 2008 with PR2 engravings on it. Now my question is this, the intake buckets fit But the exhaust buckets are too small (they are from the 2002 head), did they change the exhaust valves, buckets and cam? Thanks in advance for any help.