You are on the right path, its always best to get all options before starting. You might want to get on the Corvette boards and find out if your block is worth something. It could be worth more than you think, or it could be worth only what a standard block is worth. If you do sell your Vette block, you are stuck with pay the core charge on the reman engine which could be quit costly.
When looking for parts for your rebuild if you go that way, try and stay with one vender for the whole engine kit. It will be easyer to keep track of cost and inventory.
Also, don't forget about shipping. You will have to pay both ways. Joe