@NxCoupe , thought my previous response seemed a bit terse. That's what happens when I post half asleep, lol.
I tend to over engineer/complicate things that don't need it. I built it with the following guidelines.
1. Had be able to takt it apart to store.
2. Had to be rigid enough to move without disturbing the alignment
3. Had to be usable for any Mopar I would want to put on it.
Knowing what I know now, I'd probably just build one like Rick does at Carthage Classic Cars. Simple "I" beam rectangle with welded on supports as needed. I also like how he used an old k frame as his front frame rail location "jig". Kind of hard to mess that up.
Things I need to add to my current jig.
1. Pinch clamps for rockers. I'll need them for when the rear section is replaced and the car is no longer supported by the frame rails. Got this idea from another board member , then recently saw a post on a FB page doing the same thing. I was originally going to make some out of 1/2 plate cuz I didn't realize they made small pull clamps. I'd see the standard setup on a frame jig but these smaller clamps are perfect for what my needs.
2. Something like what Rick does for the K-Frame but I don't think I'll be using a K-Frame. I'll likely use a k-frame as a jig to build a locator fixture. I'm thinking the same 2" .180 wall tube I used for the overall jig. I'll drill the mounting holes in the ends of some tube, bolt them to the k-frame then weld support structure. Once I add these two elements I'll post details.