if you have the engine out, i would seriously strengthen your bottom end, i know your not up for big power but, why not have that piece of mind, better to be safe than sorry.. even if its just new rods, keep the standard pistons, they should be fine, its the rods that need to be stronger at that powerm, and also bearings are a must, even if they arent noisy.. n1 pump is fine, have seen them on nearly 400rwkw motors and no problems.