Check out the web sites for:
Marlin
All Pro
Downey
Trail Gear
Alcan (Custom Spring built truck specific)
Other alternatives are on the Faq section at
www.Pirate4x4.com .
Depends if you want to relocate hangers or do you want a straight bolt in. No Welding.
Decide how you want to use it before you pick height out. Also, Stay away from Aluminum lift blocks. Steel work fine but NO Aluminum.
Regarding 3" lift. All Pro's is set up more for buggy weight. Light up front.
Trail Gear has a 3" for standard weight. Not sure if MArlin has one.
Pro Comp, Super Lift Rancho etc all have lifts available for the truck. Everyone uses different spring rates on their springs. Also springs from All Pro, Trail Gear and I believe MArlin adjust the spring pin location on the front spring.
FYI my 82 has All Pro 4". I haven't wheeled it yet but the previous owner wheel it a lot and liked it.
My nephew has a trail gear 5" Fronts with CHevy 63" springs in the rear witha 2" block and it flex's well. However, he is in the process of putting 3" springs up front and taking out the block. Will do some sheetmetal trimming to make it clear 36" tall tires and keep the center of gravity low.
Good Luck
Dave