You already have a 360? If so and you like driving the car I would try to minimize down time and maximize performance per dollar spent. Head work and a camshaft will cost the same for 360 as a 318. You can drive the car with the 318 while you work on the 360. Get all your ducks in a row and when the 360 is done you can swap motors and not have all the down time waiting on machine work or parts to arrive. Plus the extra hp the 360 will produce without spending any more money than what you were already planning on spending on the 318. I don't have anything against 318's but if I were in your shoes that's what I would do.