What is the compression ratio of your piston with a 63cc chamber? Should check that first as if its too high, you will want a larger cam to keep the dynamic compression under control. Most 340 pistons were set up for 68-70 cc or 65 at smallest due to the fact that most 340 heads were large chamber design. Ni bought a stroker kit eed a lot more info about rest of build to recommend a cam.i boouht a 416 kit from scatt with flat tops 65cc heads (pro comp) its about 10.6 .this waswith a la style head