No dealer can sell the cylinders them selves for less than $875. But the price breaks start coming when buying the whole top end kit.
As far as bore size...there are two options. a 65mm bore, and a 68mm bore
With the 65mm you can still use banshee pistons, with the 68mm you have to go to blaster pistons, and change the squish angle on your domes ( for best performance). On a bolt on stock stroke application, my guess would be around 80hp with stock carbs, and (for example) toomey T5 pipes. Oh, the cubs also have better cooling capabilities also.