"My roof is gone and I am about to restore the car, can you turn a hardtop into a convertible?"
You'll need a sawzall!!!
Those two links that were mentioned are pretty comprehensive, although I didn't see a couple of things: The door glass is different for convertibles, and there is a heavy guage "C"- channel beam inside the entire length of the rockers. I think all convertibles also got the (4) torque box brackets, regardless of engine option.