It boils down to horsepower per cubic inch. You can build two different ci motors with equal performance parts, and spend about the same amount of money on each, so which one is gonna end up with the bigger numbers? A bad ass 306/347 will make more power than a mild 351/393 any day, but thats not really a fair comparison.

Whats this goin in a drag car, street car, somewhere in between?

You're lookin for 1.5 hp/ci with a 400 inch motor, totally doable but you've got to do it right.
Good heads, custom roller cam with a really good valve train, internally balanced, zero deck the block, lightweight forged pistons, piston ring gap set right, big headers, windage tray, compression above 10:1....