Reply to "351C trouble."

Usually what 'machining the valve spring pockets' means is to either increase the diameter of the pocket so a larger diameter spring end sits flat inside, and to adjust the height of the springs: they are rated at so-many-pounds of pressure per inch and are designed to be at a certain height when assembled. If they're too long, you can add flat washer-shims to tighten things up, but if they're too short, when the cam attempts to lift them, the coils hit each other. This is called "coil-bind" and is very very bad. Essentially, the whole valvetrain assembly goes solid but the cam continues to attempt to lift. This could easily have caused your troubles. Its also possible to seleect parts that allow the valve spring retainer to hit the end of the valve giude at full lift, again causing the assembly to "become solid" and destroying the guide seals. Don't get discouraged- we all make mistakes- this is called "learning from experience". I guarantee you will NEVER make such an assembly error again. I have a few mistakes of my own tucked away in my memory, by the way. As I said, a thorough cleaning will rescue most of your aftermarket parts for re-use. The first assembly was only a mid-term quiz; the final exam is coming up when you reassemble!
A gear drive will work on any cam setup, as its attached to the front of the cam and crank. A Crane adjustable valvetrain will work on any cam, with any rockerarms and lifters. But with a roller cam, you'll definitely need different springs and shorter pushrods, as roller lifters (either hydraulic or solid) are heavier and longer. Another thing that happens with roller cams in a block not designed for roller cams is, its possible to select a cam that attempts to open too far, lifting the roller wheel up into the lifter oil channel. This then creates a massive oil leak at each lifter, each revolution of the cam. Crank bearings do not live long with this setup. There are shrouded lifters (smaller roller wheels) that prevent this, or cut-down dimensionss on the cam features, or other more complicated ways around the difficulty.