Harleys have used roller followers since the year dot, since 1938 they incorporated hydrualics into them as well ,they really are fit + forget. Most american cars are similarly equipped. Even Rolls-Royce use them in their v 8 engined cars. They do not wear and are kind to the camshaft lobes too. Roller tipped rockers are a good one also, but it is near-on impossible on a vin. I will now sit back and wait to hear from some smart alec who tells me "john doe did it years ago".