If you stack blocks they could spit out, but generally the problem with blocks is the fact that they cause wheelhop due to axlewrap, because of increased leverage on the spring. In my opinion, blocks suck, but with 12" of lift you don't have a lot of choice. You could do a shackle flip to get an extra 4", with the 8" springs that'd be 12" total. You'd have 12" springs in front.
I'd personally do a 3" body lift, just so you could use slightly lower springs, like a 10" or better yet an 8". Sounds like maybe what you're going for is to have the biggest truck in town though. Be forewarned, 12" suspension lifts are not for the faint of heart. Ride quality is not poor, it's nonexistent. In my humble opinion, the max total lift I would ever go would be 8" springs in the front, 4" plus shackle flip in the back for total of 8", plus a 3" body lift for a total of 11". This would more than likely clear at least 42s, and probably 44s with a little fender trimming. Not only is this easier on the suspension and steering parts, but in your truck (which is a shortbed, if I recall), it will actually allow you to use a front driveshaft. You would be amazed to see how many trucks I see at Pismo Beach with 12" lifts that are only 2 wheel drive because the front driveshafts will no longer work.
In order to make them work and not end up with negative caster on the front wheels (that's a bad thing), the front axle needs to have the knuckles removed and turned, as well as having the spring perches reangled. The passenger one needs to be machined to do this, since it is cast into the diff housing. All of this is to point the pinion in the right direction, which is way, way up. This ain't cheap.
<font color=green>Evan</font color=green>[img]/wwwthreads_images/icons/crazy.gif[/img]