Small block all the way for a street car.SB Chevy is 200lbs lighter,Car will handle better with lighter motor in front. SB Chevy way cheaper to build. If you like to Rev a motor SB Chevy better for high revving.If you build a stroker SB Chevy with the right parts you could have the torque of a BB Chevy and the HP of BB Chevy> A lot of 383,427,434,454+ stroker SB Chevrolets in the 600+ HP and Torque range and still got a smaller motor that is 200lbs lighter. If you have a very tight engine compartment a SB chevy will easily fit and easier to access parts when working on it. Some engine bays are way to tight and almost impossible to work on with a BBChevy with headers. It is Easy to find factory parts for a SB Chevy. The BB Chevy is getting harder and harder to find Factory parts.I'm sure there is more points why a SB Chevy is better for a street car but I can't think of right now. NOw for a all out Race car, that is a total different breed of cat. More cubes the better but then you are also spending a hell of a lot more money to get that BB Chevy even bigger and getting it to rev like a SB Chevy. There is a reason NHRA Prostock uses 500CI BB not smallblocks. Like I said before that is all out racing but for street it is real hard to beat a smallblock fo many reasons.