Hey Big Dave,
I think I'd settle for feeling a little something on the take off, pass half the cars on the road and maybe only hit every other gas station! I'm thinking 396 or 427... Think that'll for the bill or am I not thinking big enough?
First thing to know about big blocks. They where designed in 1961 to be a high RPM race engine to win at NASCAR. To pay for the tooling there had to be a truck version (this was long before diesel engines where used in anything but semi trucks and locomotives) to justify to the bean counters it's existence.
When compression dropped from 12.5:1 for high performance versions of the engine (11:1 for passenger versions) down to today's 7.8:1 static compression in 1971 the motor became only a truck engine. It was still banned in California since 1971 due to it's emissions and was not installed in a car after 1974 (Camaro and Chevelle dropped it in 1973, the Nova dropped it in 1970).
A 396 has too small a bore to operate and exists only because of GM's arbitrary decision that only the Corvette and a full size car were allowed to have a motor that exceeded 400 cubes. (Ford's introduction of the 428 Cobra Jet Mustang in 1968 ended that policy). The bore is so small that it has notches in the block (that lowers compression the same way a truck 409 lowers static compression) to clear the valves. The valves do not hit the block but they are shrouded. It was to reduce valve shrouding that Chevy introduced the open chamber to replace the old small closed combustion chamber.
Because the big block likes compression (it is a semi hemi motor with canted valves and a domed piston) the drop in compression kills performance.
You can get 1.5 horsepower per cube from a small block with today's off the shelf parts. The same parts on a BBC only yield at best one horsepower per cube. So a 396 might get you 400 horsepower on pump gas but a SBC 400 will return over 500 horsepower (500 horse is the upper limit of a stock SBC block so even though you can make a lot more power, the block usually breaks), and it has 140 pounds less weight. As such if you want more power you have to go bigger with your big block.
Start with a 454 engine and you can still put 396 decals on it if you like that number. They look alike and can not be easily told from a 632 big block by most people. It is the limit of pump gas that makes almost every BBC that you see grow from a 454 into a 496 (add a stroker crank and eight bigger bore pistons on a rebuild). If you are going to drag around the extra weight of a big block make it worth your while. It doesn't cost any more to rebuild a 454 than it does to rebuild a 396; and 454 motors are easier to find in bone yards.
My Impala you see above standing on it's back bumper had a 582 cube BBC under the hood. Made over 750 horsepower and 780 foot pounds of torque normally aspirated, and had a 250 horse shot of nitrous hidden under the intake manifold.