Leamicheal, Why kill a 100% complete car? why not just build up the beaut?
What your wanting to do isn't as hard as you think. Afterall lincoln made a convertable 4 door with suicide rear doors that looked great. Just reinforce the frame for frame twist. You could box the frame for great strength and good looks, or you could just choose to add some steel to reinforce it. As for the rear doors, you don't need to weld them shut, suicide them. Just add some steel square tubing to support and strengthen the body and you'll be good to go in no time.
I'm a certafied body tech, so if you have any questions feel free to e-mail or send me a message on here.