You have a few decisions to make..
1. mechanical or hydraulic clutch
2. T56 may not fit the tunnel, so changing the tail or moving the tunnel hole.
3. custom or old tranny xmember
4. neutral saftey switch
5. key release (has to be in reverse for my car)
6. double / triple check the HP rating on your trans.. it may only be the 350 - 400 HP variant..
7. getting a shovel that has the pedal setup, or you can buy the whole kit from keisler (other places too)
8. do not believe the clutch disk you have will work for the BBC.. and I would suggest a shatter proof bellhousing if your planning on more tha a DD
LSx website has a lot of info on the 5/6 speed upgrades.
I am on travel right now, but I have a bunch of info on my computer at the house, so I will forward to you. I was going to change out my car, then decided on a different car.. now I am going for the full blown LS/T56 swap with a pro touring suspension.. OH yeah, and winning the lottery!!