It's been interesting reading this thread. I loved the link to 50cc records. What I noticed is that those bikes really couldn't get up much speed in a 1/4 mile. You are planning to run on a dragstrip right? I'm guessing you will need to keep accelerating into the run-out area and may need a half mile to hit 60mph. I think you can do it, but need room. Of course the track can't record any speed beyond the 1/4 mile trap.
When I first read the opening challenge to hit 60, I was thinking of a big motor on a trailer.
Craig Vetter's site is also good for steamlining. "rounded in front, tapered in back"
Craig Vetter, designer and inventor of the Windjammer fairing,Triumph Hurricane Motorcycle and fuel economy motorcycles