The back needs the most work. You can buy bigger sway bars for each end, the back needs that bad.
When it's all done, the rear will still move way too much for serious cornering. If that is the real goal, work hard on finding a way to install a panhard bar in the back. The tendency to roll over has a lot to do with the back end(tires) wiggling around separately from the body. The leaf springs don't keep the tires directly under the body in the same line, the tires move side to side with cornering forces. That makes it all "loose" in back, and the body is "twitching" to go to the side without the tires(rollover).
Find a way to build a panhard bar frame mounting bracket on one side. The space is tight back there, but I think a PHB can be fitted. If you do accomplish that, then the truck will handle much more predictably, which is more safe. Regards,