To me, a lot of things have to be considered before retrofitting to a roller cam. What kind of power are you making now? What RPM do you want to see? Your jet drive has to be figured here. Are you a racer or a recreational boater. How much are you willing to spend and will it all be worth it in your application. Are you thinking solid or hydraulic roller cam? Flat tappet cams can be more reliable because they have far less moving parts. When you buy a cam kit the springs may not set up correctly for the particular valve installed heights on your heads. If you are a builder , or have a good builder this will need to be addressed. You will need custom push rods lengths depending on how your heads are set up. Lifters can come apart so its wise to put more $$ into a good set. They can go from 600.00 to 1500.00. Usually with roller cam retrofits the total cost can get up 1500.00 or more by the time everything is done. It all depends on how much improvement you may see for your dollar spent and how happy you would be with the end result. Jim
My mk4 block was already drilled and tapped, as I understand it most are. I did this last year, for the first time I might add, and the first BBC I've put together in 35 years. When I asked the same questions most here said call Straub.