You have lots going on. Bang for the buck in my opinion would be tires and rims. The year one 17" rims are reasonably priced and fit. Good rubber will be a huge different feel compared to the 14" wheels. Next would be the stage 2 or 3 firm feel box. Great feel, and a lot more precision. To help with bottoming out, get a larger torsion bar set. 1" or bigger will control the front and keep it from crashing down. High end shocks will keep it all in control. These items you will feel instantly when you put them on. Large diameter sway bars will greatly help your cornering without all the understeer. Definitely a bolt on change you will feel instantly. Adjustable upper control arms, sector shaft bearing, and frame bracing will all help the overall package. The other suggestion such as welding the k-frame will help, but you won't necessarily feel the difference if that is the only thing you change. Same with bracing the lower control arms.
The majority of your symptoms will be cured with wheels and tires, a new steering box, torsion bars, expensive shocks, and sway bars. That will cost you a couple of grand plus, but will change your car more than you can believe. Then do the little stuff that will add up over time.
Hotchkis TVS is a great start without going overboard with rack and pinion and coil overs. Thats chevy crap.