Some more stuff for you. Rubber body bushings for one. I couldn't tell the difference when I put on poly, but my rubber ones were pretty tired, so that might have had a perception effect.
But rubber should at least in theory give you better road noise isolation.
Same for leaf spring bushings.
And if you can find a way to put rubber or poly insulators at the top and/or bottom of the coil springs, like most cars had back in the day, that could help as well.
Is the body coming off the frame for paint? Whether it is or not (just easier if it is) I would seriously consider products like Lizzard Skin sound and heat barrier spray on coatings. Whether inside or out (I prefer out, but either works) it will go a long way towards keeping the interior tolerable in winter or summer.
You didn't say where you lived, but are you planning on adding A/C to the rig? If so, it will thank you (and so will your family and friends) if you add plenty of sound and heat insulation.
The spray stuff is great because you can get it where you don't normally get the stick-on stuff. Up inside the wheel wells, all up and under the firewall and cowl area and the doors. Every nook and cranny.
We have our Racket Jacket system:
https://www.wildhorses4x4.com/category/Bronco_Carpet which works very well. But adding a Lizzard Skin type spray coating can only make everything better. Heck, even just carpet and jute backing is a huge improvement over bare floors or mats, but as in the case with electrical grounding on these rigs, more is better!
Headers are great for performance, but cast-iron exhaust manifolds are just quieter.
Seal up the body wherever you see a hole. Even if it's in an out of the way area, it lets in noise. Renew the window wetherstripping will often (more often than not?) quiet things down as well.
Insulate the crap out of a hard top if that's what you're using.
Yeah, I know I'm concentrating on NVH rather than handling like you were asking about. But I've found that the noise and heat inside the cabin of an EB will go a LONG way towards driver happiness. Just feels better inside and lets you concentrate on driving.
Not trying to overlook the more important aspects of handling and braking of course. Just adding to the solutions.
Sorry if you're a long time old-car guy and knew all that stuff already. But at your first post we don't know all that so I'm just throwing out what might be overlooked if you're not familiar.
Good luck.
Paul