That Javelin is sweet.
They are only a survivor with original paint once. If you can save it in clean presentable shape that would be pretty cool.
I don't know squat about AMC aftermarket suspension but I was in a similar spot with my Torino or worse. Nobody made suspension parts that would really bring it to the level of handling I was hoping for. No R&P steering kits, no subframe connectors, no rear 4 links, 3 links or truck bar set ups ect ect.
So I went the full chassis route with the Roadster Shop. There seem to be some nice bolt in kits for yours but add up all the cost maybe bolting a complete chassis to the body might not be that much more.
Ask a lot of questions and plan it out with a few different scenarios before you buy anything. As the old saying goes, measure twice cut once.
Welcome, sweet car