What if I use leaf spring spacer blocks for lift ? How much do you think is ok so if I pull the weight out I will still be in tolerance and not risk having the drive shaft in the wrong place. I had a shaft come out on a 94 F150 and shred the teeth on it by lifting it like this and removing the weight.
Bilstein are great shocks. I'd recommend a set of their heavy-duty shocks for your work truck, and don't look back. Instead of playing with lift, put on some helper springs that will let you carry the load without affecting your stock ride height and steering geometry (remember how you shredded that '94?). This is a work truck, not a toy, so keep it simple, and close to stock. If you can't find any parts from the forum sponsors, JC Whitney comes to mind as the ideal place to find helper springs.
I put a set of Monroe Gas Magnums on my truck and they seem to do all right. I've only ever carried one really heavy load, and that was sitting on the overload springs (almost frame snubbers), so I can't really say how they'd perform in daily work duty.