New to forum and Dodge Demon Clone Project
Here's the simple way to think of it. Unbolt all the body parts from the firewall forward until all that's left are the inner fenders and bare rad support (the items that don't unbolt). Those are all the parts you need :)
Of course you cannot unbolt the tail panel. A propane torch will remove the solder from the joints. Then get a spot weld cutter and go at it. WD 40 will make your bit last a lot longer.
I imagine you know the Darts from 70-72 use the same front clip. The grilles differ between years.