I'm amazed that anyone could be bothered going to a National meeting with all the BS regarding eligibility. The rules are hypocritical, ambiguous and open to any interpretation anyone wants to put on it. I doubt any bike in any class would be legal if someone wanted to push the issue. Then there's the "blind eye" mentality depending on the rider of said bikes. Glen Bell's CR480 is a prime example amongst a miriad of others. I ride VMX bikes for fun not for full on head f*&k! For what it's worth Doc, I believe your swing arm should be Pre'78 legal. Even though it may be a "C" arm, it's way more "of the period" than a set of tapered bars, and you could argue which of the two gives more of a "performance advantage".
Cheers,
K