this is pretty easy i think....
for the front-- use sheet styrene and cut a rounded triangle big enough to mount the wheels on. figure out how low you want to go, use that to measure how big the triangle needs to be, it should connect to the frame. if it needs to be real tall you may have to create a brace on the back to support it. in order to mount the wheels, cut off the stock mounts and glue them in where you need them, triple check measurements to be sure the the same on both sides other wise itll be wonky
for the back-- again figure out how low you want it to be, then there are two ways. easiest is to cut the leaf spring til they fit on the frame when at ride height. harder but better looking is to get rid of the leafs all together and make coil overs. i found a good way to do this is to use round styrene rod and the springs out of old click pens, make them however big you want and then apply so the ride height is where you want it..
this is the ways that ive used and they have worked for me. good luck, hope i helped.
marc