PISTONS: Flattop or Dish for stoker....

With lets say 450 hp going from 8.5 to 10.5 will net you around 26hp.
You can run around 11.1 with 87 octane if you choose the right cam and use a quench dome piston or closed chambered head and the timing & curve will be very important here.
The .509 will turn a 10.5 340 into a low cylinder pressure pos, were talking 120psi or less cranking. That .509 cam is tried and true but I hate it, it's an OLD race piece, a light switch cam if you will, and I don't use hydros to race so it's worthless to me.

Go to engle cams site and check out the KV-3 AND KV-4 solid cams they are the next best thing to a roller.