I cant remember what the spring installed height was that we were getting with the retainers that we had mach'd up but im guessing that .750 would be about max lift at the retainer after lash and pushrod deflection. That would be using a 2.02 installed height spring. Im just checking the Isky tool room springs catalog however. I just cant remember what installed height I was getting when I was initially setting up Bobs Victors were. If we could get 2.0-2.02 installed height then I would guess a cam with .780 lift would be pushing it and .750 after lash and deflection. I am also not sure as to how the valve geometry would be affected by installing longer valves than what Edelbrock lists. That would give better spring installed heights but the geometry would have to be checked.