Nice find.
Actually the FOX bushing versions of the ball bearing engines only lose about 200 to 500 rpms or so off the top end.
I actually tend to prefer the bushing versions of the engines. They run good and don't really lose that much power. Plus you don't need to worry about ball bearings going bad on you.
At the time FOX made the bushing and ball bearing engines the same, except for the bearings. So it was a excellent comparison of the effects ball bearings really had on a engine. Later FOX changed the port timing a little on the ball bearing engines, but by then I think Fox had stopped producing the bushing versions. Other companies that had bushing versus ball bearing engines of the same displacement, had made the engines wildly different. So you could not compare them to see that a bushing version runs almost as good as a ball bearing version. Anyway it used to aggravate Mr Fox that people put so much emphasis on the marketing claims of competitors that ball bearing supported cranks was the way to go.