Rear leaf springs for 68 Firebird - LS1 swap (i have two sets which should i use?)

[Shawn MacAnanny]

So I'm finally ready to install my rear end in my car. I have a set of summit adjustable shocks, i set them on the softest setting. I also have a set of lakewood traction bars that will be going in when i put in the new rear. The rear came out of 74 Nova. It's an 8.5 posi with 4.56 richmond gears. When i bought this rear i also got a set of springs with it. They have about 5 or 6 leafs on them. I am not sure if i should install these 5-6 leaf springs with the rear or keep the multi leaf (like 3 or 4) leaf springs i have on it.

The car will make about 460rwhp-480rwhp (once i install the heads and tune) it will weigh around 2900lbs and I'm running a T56 6 speed in it. My entire engine sits rearward of the k-member. Also i have moroso (i think) subframe connectors as well. I'll be running 26"and 28" Mickey Thompson ET Drags at the track and 30" Mickey Thompson ET street radials on the road. My car also has adjustable shackles installed at the rear. The 26" slick clear with plenty of room on the lowest setting.

The front suspension is a mile in the air right now fromt removing the Pontiac 400/400 and installing a 400lb lighter setup. Any suggestions with that as well? I run Mickey Thompson 26" skinnies up front. All tires are on aluminum Centerline Telstars. I've read cutting the springs, getting drop spindles and all but i plan on running disk brakes up from shortly. With this car i PLAN on beeing able to get a foot or so of front wheel lift. That's what I'm hoping for with 4.56s and sticky tires with a nice launch. Can ya'll help me setup my suspension for that? This will also be driven quite frequently but my standard of driveability is about on par with that of 'track only'

Thanks guys!

[Shawn MacAnanny]

No one? I can get pics, numbers, or whatever you need me to help me decide.