Step 2. Determine you budget.

Step 3, determine your budget.

You get the picture.

I also agree with the question about the piston and compression ratio. If it is truly original, then we know pretty close where the piston is relative to the deck. If it has ever been rebuilt, the piston top/CR can be anywhere. I don't think original type pistons with the correct CD have been available for 40 years for the 383.

If nothing else, you should get a cranking cylinder pressure test now. Even though we don't know the cam, it might still be helpful.