Rohan, It is not the eras but the type of bike which should determine eligibility to race. Three heats fixes all differences in speeds. If you take any thirties four stroke single and fill it full of 2013 parts, it will go quick. If you take a Scott Squirrel two stroke and do similar, it will hose off any fourstroke. Historic racing as we know it is bullshit. There is no class for my Seeley Commando 850. What I want to race against is Ducati, Norton, Triunph, BMW, Moto Guzzi, aircooled singles twins and triples - THUNDERBIKES. Not two strokes or four cylinder superbikes. What we see in Australia as historic racing has no spectator or competitor appeal - nobody really races, it is a procession which looks like traffic on a freeway. - BORING and EXPENSIVE !
If I had my way I'd start the concept of classic racing , and hold the Australian Classic TT, Australian Classic GP, and Australian Classic Superbike Championships. And I'd run cross period with slow and fast heats and finals. In 27 races we could cover three capacity classes for each major type , and three heats. - One day's racing !
In the olden days when we raced, we got a ride in a heat, and in a final if we were quick enough. We got a ride in the next up capacity class for heats and finals, unless we had an Unlimited bike. We also got a ride in the next higher rider graded race unless we were A graders. These days it is all in togerther r gardless of major differences in racing lines or speeds, it is all based on date of manufacture and capacities - IDIOCY.