if its all stock i.e. compression, manifolds, valves, springs, rockers, torque converter, etc. id say go for the smallest voodoo cam, the 60800. it'll be a pretty nasty mismatch with a big cam such as the ones you have in mind. its generally better to under cam a street car rather than over cam it, you'll hate driving it otherwise and it'll feel like a dog. even with headers, better springs, valves, better compression, rockers and induction i wouldnt go much larger than the voodoo 60801 or 60802 cams in a 350. especially if you plan on driving the car frequently..... i dont know about elongating the rockers but i'm sure you'd need properly sized pushrods