Running toyota rear springs (pickup or 4runner, doesn't really matter) in the front is really common with the toyota folks. The center pin is located more towards the front of the main leaf, so they move the front axle forward compared to the waggy springs, but where your axle actually ends up depends on where you put the hangers. This is great for approach angle, but will usually require a new driveshaft. Put some big tires on there, and front bumper will just about line up with the front of your tires They are very flexy and most people shore them up with additional leafs if it will be driven on the street.
This is how they line up on toyota spring hangers, just for reference:
http://sphotos.ak.fbcdn.net/photos-ak-sf2p/v649/97/11/77200125/n77200125_31672395_6788841.jpg
