Ben,
Another thing to check woul be the oil screen. It is accessable by (i believe...) removing the oil pan (requires pulling pipes and probably headers too). There is a large nylon bowl type assembly with a stainless screen in the bottom of the part. It feeds from the oil sump into the oil pumps. If there is a lot of slime in yours, it could impeed the oil flow abit too. A long shot, but since seeing all the crud and bits in Jaymos when we had it apart, I would not rule it out. A winter project for sure. You would probably need to lift the bike and support it then remove the jack for lots of working room underneath. Not an easy job, but you could do it, it's just a lot of little bits to get out of the way first.
There are also three small oil feed lines in the motor, you saw the one on top of the cams right? There are two more like that and I would think a very small amount of gasket material/RTV/Dirt could easily clog them by 50% at least. Look through the shop manual and you'll find them. One of them is also on the nylon screen res I mention above. I beleive the last one was behind the right hand shifter cover, down and behind the magneto cover, oposite the shifter arm.
