Back in 1994 I went to the IDBA World Finals in Memphis. I know this is pre-Busa, but bear with me. Ther was in one matchup, an extremely built big-twin evo harley up against some production based, and definately built jap big bore 4cyl. bike - I think it was a gixxer 1100. In the first 1/8mi., the harley owned the jap bike, and I mean OWNED. Blew his fairing off - so to speak. Then almost instantly, the jap bike passed the harley as if it was standing still and blew the harley away in the final 1/8mi. In the end, it wasn't even a race, But in the beginning, the harley ruled. So, in answer to your question, yes, I think that a properly built harley with a good rider can take a stock busa in a drag race of 1/8mi. or less. I also think that once a harley hist 100 mph, it hits its own wall of wind resistance and can't do much more.
Gar