Your typical B body like you're describing will likely be around 3700-3800 lbs. You'll need a REAL 825+ HP at the flywheel to run the number you want.
You can build a stout, but streetable, 512 and hit it w/ a 200 shot every now and then to go mid 9s.
Or go big or go home w/ the 512 and put some decent compression in it, E 85, and bigger heads than the Trick Flows, nasty roller and try to go mid 9s on motor. Either way, the stock block will be a time bomb.
Or do like I did and get a strong aftermarket block and build a big, but streetable, 572" motor that'll run mid 9s all day at 3800 lbs on pump gas.