You can't just put spacers on the shocks to raise the body, you'd also need longer sway bar links, aux tank fill hose. Also you would need to fab brackets to lower the rear differential to keep the CV angles correct. TOO MUCH WORK !!! Yoo'd be better off just changing gear sets and staying with stock tire sizes.
You could make spacers that would only lift the fiberglass body, doing it this way does not change the suspension angles.
Jeannie likes the wheels I linked to, not your selection