Outback, an add-a-leaf would be best. I'm assuming that you have already stacked blocks to get to the 6 inch lift. Short of one single block to get that 8 inches of lift, an add-a-leaf and the existing stack should get you where you are trying to go. BTW, I f'in hate stacked blocks, 25 years ago, magazines wouldn't publish pics of your rig if it had stacked blocks because they are unsafe.
Up front, well, it's not quite so easy. With coils, simply putting in taller coils, or spacers fot that matter, has the equal and opposite effect of inducing negative caster. Negative caster is from the axle rolling forward when lifted. To correct this, you either need to add caster shims, or lower the trailing arms in the rear. Either of these will correct the negative caster that taller coils or spacers will induce.
Unless you go to a custom pitman arm, most "out of the box" lifts use the same pitman arm for 6 and 8 inch lifts. There will be enough adjustment in the drag link to compensate for this. This is one time when I think that an adjustable track bar AND a track bar drop bracket should be used. It is mucho importanto to keep the brag link and track bar parallel. Therefore, if you're not going to drop the pitman arm again, then don't dop the track bar again.