Mike the best I ever got was 23.5 bhp. That was the last time I tested which would have been back in about 1999. I was running exactly the same set up as I do now, except for the ignition, which was my advance retard motoplat. I expect its the same peak power output with the rex caunt ignition, but with more torque between 8,000 and 9,000 rpm.
Your best bet is to leave everything alone
Cheers Pete