You will need two normal length head studs to replace the long water outlet studs used with the model A head You will get near a seven horsepower boost and the model B water pump is a big improvement over the A pump. It cools noticeably better and doesn't have as much tendency to over pump out water around the radiator cap and out the over flow tube like the model A water pump will. The C head is the poor mans high compression head. The improved heart shaped combustion chamber is a huge improvement over the A head There are dyno tests on the Piranio web site that shows the results of a stock model A engine with a C head and no other mods. I have run these heads and can tell you for sure that there is an improvement You want notice as much improvement as a 5.5 or 6.0 head but if you need a head and already have the C head, I would sure use it.