My original 72 Mustang 302 still runs great for every day driving, but it has lost a lot of thrust over the years. It has been suggested to me that I might considered replacing the CAM. New 302 engine I have been told is 3 K. Should replace the CAM and assorted other parts (ie. lifters, etc). If I go with a new CAM, where is a good place to buy one. Or is this expected to left to the shop that install it so they can make extra on the parts?