I have found that hiems make a world of a diffrence with radius arms. More so if one is wristed. With the stock pancake style bushings, you tend to limit what your suspension can do. The busings are good enough for a mild non wristed lift, but soon, they will bind, and limit how mutch flex you can obtain. Hiems will give you smoother travel while flexing, they dont bind, and they allow a greater range of movement wich is perfect if you have a 3 link suspension design. When i changed over to hiems, i found that they freed up a good 6" of flex. To the point where coils are flexed out. *time for a limiting strap or coilovers now* Another option you can use, to avoid the road vibration that you gain with hiems *far to many people bitch about that* Is use the same style bushings that you use on your leafspring eyes. I forget what the hell thier called. They will allow the same vertical flex and movement that a hiem will give you. They just take up a little more space.
If you deside to stick with bushings, use Rubber, not poly bushings. Rubber is more squishy and allows a greater range of movement that that of poly bushings.