The way to check for sumping is typically to run it on the dyno under full throttle and shut it down immediately and pull the small plug in the crankcase right under the flywheel and see how much oil you get out of it. I've heard anything over 6 oz. is enough to cause sumping. I've also heard some say you shouldn't see more than 4 oz. I'm not sure what the magic number is. But the clearance between the flywheel and the bottom of the crankcase is very tight and too much oil in that area will cause loss of power because the flywheel is literally having to spin through it. It happened on mine so it can still be a problem even on the new twin cams.