Where to start on repairing this Demon???

First off another car can only be used for idea's, anything under 1/2" clearance (compared) is worthless as these cars are so different...

If i were going to do that i think i would remove the deck lid, and install the rear panel (just tack) and then see where the 1/4's lay.

Also before you do anything you need to fit the hood to the body, then the front panel and fenders, rebuild the door hinges and gap the doors to the fender and rockers. With this you can not hang the 1/4 and adjust IT to the rest of the body and tail section.

Something to think about is that is about what the factory started with, a body in white...