Does anyone have a Demon skeleton laying around?

You don't know. You never fixed a frame or assembled a body in your life in your life. Just a bunch of words with pictures you load from the web as always.. Lets get a picture of your unfinished Dartster as an example of your experience. The half Dart Half Duster with a Scamp vin. Lets not forget to mention your 18's and your kick *** suspension and Hoody scoops.

Actually I’ve fixed several frames and assembled many car bodies in my life. You wouldn’t know.

No point posting pictures of my Duster, haven’t needed to replace any chassis members on that so it’s not relevant.

Not sure what your problem is, I said from the get go that car of the OP’s should be on a frame table so on that we’re in complete agreement. You being wrong about something unrelated in another thread that got closed is no reason to bring the argument here.
All arguing aside, since no one had the dimensions I was looking for, and also since my car is not on a frame rack or level floor, I may have found the solution another way. I pumped up the back tires to their normal psi then leveled the rear axle (from left to right), then put a level between the left and right rocker and leveled them (from left to right), then put a level on the top of the firewall and leveled it (from left to right), then put a level on the bottom of the radiator support and leveled it (from left to right). So that leveled the car from left to right. Then for the front to rear tolerences I hung the doors and fenders and slightly adjusted the nose up or down to insure that all the door/fender lines were uniform.

And so far it looks beautiful, all the fender mounting holes line up nicely, and also the spot weld holes line up with the new panels. I also am guessing that the weight of all the new parts on the front end will stress/weigh down the front of the car, so I'm building a slightly bigger gap between the doors and fenders at the bottom, that will close up uniformly once all the front end stuff is installed.

That’s a start for sure, but you absolutely can not expect to use the body components and those fits to locate your suspension points. It’s just not gonna be close enough. You could end up with great door and fender fits and a car that dog tracks down the road and can’t be aligned. The factory managed to get cars that had lousy body fits to have straight chassis’s, so there’s no reason why the inverse can’t be true.

You need to be able to drop plumb lines to a level surface. Ideally, you’d need something like that frame jig OMM has. But yeah I get why you might not want to deal with him!