First off, you need to learn to walk before you run. Before you spend a dollar on the engine, you need to do your research. Any Good engine builder will tell you to decide exactly what you are looking for the engine to do for you, ( high rpm, low rpm, high horse, torque, car weight, differential gearing, longevity etc...) and once you decide the combination, stick with it. The biggest mistake you can make is to start changing your mind in the middle of the build what you now think you want.. Building an engine is like preparing a meal. Use the wrong ingredients or cook at the wrong temp for the wrong period of time and you end up with something that you won't like to eat. Learn to use a recipe book first, than create your own later.