If you really focused on going LW with a BB and used an aluminum block etc you could probably get to a relatively similar spot weight wise as a SB however this seems like a lot of work (and money) for not a lot of gain. That said, I guess it all depends on what you are doing or want to do. A properly build SB can and does produce quite a lot of HP. Could a BB be made more powerful, sure as there is not replacement for displacement but to what end I guess is the question. If you are trying to build a road racer with 1000 HP you might be over looking what you are trying to get as having too much power as a road racer might cause more problems than it solves. There are plenty of people making 600+ HP with a small block, so I am not sure what the attraction would be to go to a BB. Dont get me wrong, I like my 440 but I also like my 416 SB; different strokes......