All engines that don't have reeds are piston ported except rotary valve units----probably other exceptions. What you are looking at are transfer ports or boost ports. If the transfer port extends to where the cylinder contacts the case you would need to make the case match up. The boost port configuration with port holes in piston are the easiest to mod a stock cyl with and help cool the piston crown as well as provide an additional route for case gasses to enter the combustion side. Whatever you see on these kits you can do to a stk cyl if you can squeeze it all in.