This is one of the more difficult areas to describe. I set out with an idea where to start, but I have changed the front spring several times and am probably not done yet.
The basis for my front springs are the top two rear main leaves from an 86 Toyota 4x4 truck. There are several reasons for these springs. First, these springs offer a main leaf and a second leaf with the military wrap for added safety & strength. Secondly, when used as a front spring, the center pin position moves the axle forward 2" from stock, offering better tire clearance and the ability to run less lift and a larger tire. Third, these springs are roughly 2" longer than the stock Toyota solid axle front springs. A longer spring like this generally means more droop.
Once I had decided on the top two main leaves, I had to decide on the rest of the pack. I was trying to save as much money as possible, so I was determined to use the variety of spring leaves I had available on hand. Back in 98 I had purchased a set of used Rancho 3" front spring for an 85 & older Toyota truck. I also had a few sets of rear springs available front an 85 Toyota, as well as some leaves remaining from the Isuzu pack I had used for my first rear spring swap.
The initial pack I used after the swap was a mixture of the Isuzu leaves and stock Toyota rear leaves. This pack turned out to be extremely soft - I could stand & push the bumper of the truck down about 8" with just one hand. This pack also did not give me the amount of lift I wanted.
The next pack I tried is the one I am presently running. It consists of the following leaves (top to bottom):
This pack has worked well over the last few months, although is has settles about .5" on the passenger side. I knew the Rancho 3" leaves would give me a pack that had about 2" of lift to it. The rest of my lift comes from the lowered spring mount and shackle hanger under the frame. In all, I have somewhere between 4.5" and 5.5" of lift on my truck.
These springs flex really well, and I must say I am not disappointed.