Cregnybaa, you / your rider have my utmost respect for running a standard frame, I was talked into an "adventure" off the 2 stroke road into the Senior MGP once on a GSXR750, by the end of practice week it had been christened "The Flying Hinge", there were loads of RC30's in those days, I started at 70 and have pics of RC's and OW01's behind me on the line. Wonder where all those bikes are now ?.
Just asking out of interest / hypothetically - If the regs allow big engines and bespoke period frames/components etc what is there to stop somebody putting a big cc motor of any description in a ZXR frame and entering it as such ??.