Hey I'm running stock leafs on my 77, 4 door. the back end is sitting normal, even with the front but my friend at school has 5 leafs on his 69 camaro and it lifted the thing just a little. what will lift the rearend on mine just enough to make it a little taller in back then the front. 5 leafs seem like too much. also my brake light has just started screwing up. i changed the brake swicth months bacl but now the brake lights work in park perfectly but only work when in gear if you have the brake pedal to the floor or my turn signals running while I'm braking.
Go to a junyard and get some extra leafs that are the same width as the leafs on the Mav and bolt them on to the Mav's main leaf. You'll have to experiment some, swapping leafs in and out to get the height you want. The current from brake light switch goes through the turn signal/hazard switch in the column before it goed back to the lamps. Your problem could be there.
If you are going to start disassembling everything maybe just get a new set of springs. I believe a lot of places can customize your order to make a lift possible. I bought mine from ESPO in Danville,PA but i just looked on their site and didn't see them listed??
http://mmb.maverick.to/showthread.php?t=49782 Check this out. I used this tech tip for my Comet and for 50 bucks you cant beat it. I used the 2-4 and 5th spring off a ford econline van and it raised my car about 1.5 inches. I dont bottom out anymore and it is not too firm for rough roads.