Unless you have really flexy springs or are going with a link set-up that would require it you will probably see little to no benefit to going with a pan-hard with good springs and quality poly bushings.
Pan-hards are to control the lateral (side to side) movement of an axle, parallel leaf springs with u-bolts and good bushings do a pretty darn good job of that on their own.
Now a sway-bar would make a difference, and Scout II's already have a pseudo-sway bar in the front with the bar between the shackles, but proper front and rear sway bars, properly sized could improve the handling and cornering of a Scout, especially one geared toward the street.
