Yes, the last page contains the results of my experimentation. You'll get the biggest boost simply from proper jetting of the carbs, which is also the easiest and cheapest. If more is wanted the expansion chambers will provide the biggest improvement. Don't cut the rotary valves. They are already timed quite aggressively for road use and with anything short of continuous high rpm racing you'll sacrifice too much low end for the tiny bit of top end power gain. Porting gains are also not very substantial, but small improvement can be had there in exchange for considerable effort and cost. I'd only consider it if the cylinders need replating anyway.
Regarding the expansion chambers, one idea I had toyed with decades ago was variable length chambers (slip joint on the header pipe) combined with more aggressive cone angles for bigger boost. It was more difficult to accurately control back then (manually) but today would be relatively easily controlled via a widely available hobbyist microprocessor board controlling linear motors.
Be advised that even with the internal stingers and glass pack silencers the single wall expansion chambers are LOUD when when going WOT. I could be heard across town so could not fully utilize the power without attracting the attention of the cops. Stealth is a big advantage.
