When I was in the peak of my racing career it was the mid nineties, I was riding a Husaberg , It was without a doubt state of the art machinery. there was a guy in our club(HDMCC) at the time named "Mick", he'd turn up at enduro-crosses, cross country's, Enduro's and the like...on a 81 KX420, it was a real peice of shit!, Mick won the enduro, cross country and Pony express club championship (Clubman Class) at least once on that rig, and had passed me (Being A grade at the time) on it on several occasions.
What I am saying here is that all this piss whinning about a poofteenth pubic hair outside the bitch factor regulations is all crap, these guys protesting are just girlie-mans and mostly it don't matter shit what you are on... it comes down to riding ability.
Look at the guy who won the pre 85 in Tassie, you can't tell me that a 490 Maico has even a scratch on a 84 CR500? Honda at that time were sinking millions into HRC and motocross bike technology whilst maico were wiping their dirty little German bums getting ready flush the whole shit fight.
still, who won the event in Tassie?, the guy with the riding ability and the fitness.
Bring the RC450 replica's on I say, if it is a true replica and it is within the air cooled/drum brake/ non-linkage rules.... let it ride (The guy on the german crudmobile is gunna blow him off anyway!)