If you are looking for torque, go for it. Pontiacs have longer rods and stroke, so there is a lot more low end torque. Don't try and rev it though. The crank doesn't agree with the rods after about 5500 rpm. A Pontiac 400 has BBC type torque, and only weighs 50lbs more than a SBC(with aluninum intake). As far as building for cheap, the pistons are the only thing that are more expensive. Check out
www.classicalpontiac.com for engine building. You would be suprised at how those old engines perform.