Your 4 door will be best as it is longer. All of the trucks pull pretty good. Honestly its a toss up. The 6spd will pull great. And the current truck will be easy to pull but you will most likely need a tranny. However the 6spd truck will need a nice clutch and flywheel.
Street stock is a 2.6 class so you can run a decent turbo. But if you dont have the cash for that or a tranny stay in the work stock class.
You will need safety equipment which includes.
Kill switch(electric or air depends on rules)
Driveshaft loops/explosion sheilds
Turbo cross bolts
Stack or turn up tip
2lb fire extinguiser
maybe a helment and fire jacket.
Now for traction you may know what to do but.
Build some LONG traction bars out of Schedule 80 pipe and make nice brackets than spread the load out over the frame. I hope to make write up on my new ones sometime.
Suspension stops that lift the frame about an inch. So a 9 or 10" block will work if you truck has stock leafs. Make it adjustable too so you can have 1" of travel when required
30psi front 50 rear is what I usually follow.
If you can hang front weights do so.
Tie rod sleeves and if you plan to makje more than a couple hooks, a straight centerlink.
And of course lowering the Tbars.
Now for tires, if you can afford to, get a set of dedicated tires. If you are under 600hp run BFGs, something like 315s.
If you may be over 600 or close to it try STSs 33x12.5
You will also need a strong adjustable pulling hitch with an eye that measures 3x3.75" to incorporate the new hook.
Really need to know the budget though to tell you waht to do for power. The edge will have to go regardless.
Read my how to pull write ups here
http://www.dieselhaulin.com/forums/sled-pulling/1338-sled-pulling-faq-tips-tricks.html