[mickmate]

You'll want those at a minimum to tie in some steering, door hinges, windscreen and strikers etc. Sounds like quite a jigsaw puzzle! I'd consider hanging it upside down from some slung straps and adjusting the body to the right flatness, heights door spacings etc and bond in the other parts. Then see what structures you can tie into. The dash hoop is usually tied forward to the front suspension.
Good luck with it.
Cheers Nick