Possibly time to split cases unless your jetting is so far off or the air filter is way over oiled, but not having a noticeable bog makes me think otherwise (are you using race gas or a higher octane fuel where the previous owner had it jetted for a heavier or cheaper fuel , the jetting could be quite a bit off but that doesn't entirely explain the seepage on the bottom of the cases unless there's so much unburnt fuel pooling down there it's seeping through the sealent, which the cases would have to be split to resolve along with correct jetting). Sounds like you could have a multitude of issues, strange fuel seepage could be coming from the center cases if sealent between the matched cases is deteriorated. Clutch side crank seal could be to blame for the excessive smoke, especially at higher rpm's. Have you noticed a loss in tranny oil or a little less when changing?
I'd start with pulling the ignition cover off and move the flywheel up & down to check for big bearing play (a bearing going will stress the piston & rings, you'll have to replace them and it'll cause the crank seals to leak air and/or tranny juice). If you've had this bike a while & haven't replaced the reeds, I would do so. Who knows the last time they were replaced, I replace mine every top-end (for a reason, they affect performance when they're slacked). Measure the amount of oil going in & measure what comes out at an oil change after, keep an eye on the site glass to make sure if it is consuming it that you don't run it too low, but if you're getting less out by a noticeable margin, your crank seal on the clutch side is bad, gotta split cases. When was the last time the powervalves inspected and/or cleaned? It's fairly hard to diagnose a running issue over the computer, but those are the starting points from what you're saying that I'd start with.
