Puller only?? I would say find a wrecked 3rd gen. I think as soon as somebody breaks the rev limit, the 3rd gens will have big power, especially in the street class. I wouldn't be afraid of a 24V truck, they are much easier to tune, light the chargers easier, etc. A HRVP, blue chip reline box, and a set of big injectors, you will have a lot of fuel. Manuals appear to be harder on the drive line, but are cheaper to mod, especially if you go with a 12V, they have a better pump(96-98 12V) than the autos. Put big money in the auto once and you will be good to go for a long time. There are a lot of turbo options depends on how much you want to spend, and if the rules require it to bolt directly to a stock manifold, allow you to bush it down, etc. I really like the FASS systems. You might as well figure your gonna need to put another at least another $6k in the truck to be competitive.
Unless your dumping big money in the engine, the auto will outpull a manual. Look at the top trucks in the street class.