I have a replica RC450 which I've never had plans to ride, but I just might take it to a race meeting to see what would happen. I'm sure I'd get some amusement out of watching the eligibilty police have kittens at the thought of it hitting the track, WHICH IS WRONG. It is air cooled, twin shock , drum brake in a 1979 chassis.
In the other thread, everyone seemed to agree that drum brake forks from a non-Evo bike were OK when fitted to an Evo bike.
So why would an air-cooled motor from a non-Evo bike suddenly be a big drama?
In more general terms, we're never going to be able to
faithfully recreate any specific era.
Look at vintage road racing, historic car racing, historic car rallying, etc etc - in
every case, there are machines built far in excess of what anyone ever did/could do back in the day. If
nothing else, tyres and brake pad materials are heaps better, and you're never going to stop that.
This happens for a number of reasons, but the two main ones are a desire to be as competitive as possible, and simple parts availability. The competitiveness side of things can be debated, but the parts availability thing is crucially important.
For example: Everyone keeps bringing up shock absorbers ("what about those brand-new, fully adjustable shocks!?"), but could you imagine the shit-fight that would occur if we mandated that all pre-75 bikes had to run shocks made before 1975??
One of the constant themes of the VMX rules is that there have been no restrictions on consumables (tyres, sprockets, handlebars, etc), and minimal restrictions on the semi-consumables (shocks, exhausts, etc).
If we now feel that those components have developed to a point that they're no-longer VMX-friendly, then that's fine... But if that's the case, we need to sit down and collectively decide what is and is-not acceptable. To just shoot from the hip and demand that our individual point of view is THE single correct point of view is going to get us nowhere (unless you consider forum bickering to be somewhere...).