Frank,
Thanks for the comment about a potential article in LFM. I have sent Colin a file of info and shared a willingness to write something. We are talking about it, but it may be a while.
Bing,
Love the truck, love the stance, you should be proud. Are you still going to Columbus? I know everyone there would love to see the truck.
I just read an article in the July 2009 issue of Hotrod & Restoration Magazine (a trade mag). It reminded me of the need to make sure the pinion angle is where it should be to keep the needle bearings spinning properly in the rear u-joint (especially when you drop it 6 inches). Traditionally the engine/transmissions are mounted with a 3-degree downward angle and the pinion must be adjusted with leaf spring shims to a 3-degree upward angle. This keeps the driveshaft level and those bearings spinning. I lowered the rear axle in mine, but I didn't give it enough upward pinion angle. I needed to change that as the u-joint bearings got a little flat last season.
57f100
In your last question about just leaving 3 leaf springs and leaving everything else alone, this is what the stance could look like.

I ran this 57 (I used to like 58 grilles better) on the street for 20 years like that. It did fine with only 3 leafs left, but make sure they are the top three. It could get a little bouncy, but new heavy duty gas charged shocks will help.
As I mentioned before, I always got the stance I wanted, but not the performance I needed. There are many areas for gremlins to show up and rob you of the ride and steering quality that was experienced by owners when the trucks were new.
No matter which way you go, attention to a few small details will help. Charlie Mc mentioned that he purchased new bushings and shackles, very important. Anything to tighten up the axle will help (I currently use a panhard bar). Another thing to look for is worn bolts and bolt holes in the spring hanger. Attached is a picture of the egg shaped holes that were in mine.
Before...............

After welding the holes and redrilling.............

As a final note to this post, all your hard work may still be disappointing without a trip to your local front end alignment shop. Modifications and repairs may only be half of the job needed, new shocks and a proper alignment including toe-in is easily the other half.
Charlie Burns Laton, Ca (South of Fresno)

BurnsRacing981@gmail.com