S&S has some stroker cranks as well as big bore kits. I think that the same problem with all V-twins here is the size of the piston and the largest not having skirts unless the cylinder is longer - that causes fit problems and frame modification. The sportster engine has 4 seperate cams and the best valve geometry of any push rod V-twi. Stroked and BB, properly balanced, could easily get 7500 rpm and maybe more. That is where the power is. A well done sporty motor kicks ass. I saw some articles that had cut the trans out of the engine and modified the cases to fit in a softail frame. That bike could be a real sleeper.