318 power?

Less money! 440source has full rotating assemblies that start at $2K. For the price of cylinder heads, B/RB vs SBM’s, the power return makes SBM’s look like a bad choice.
Yes the big blocks make more power or torque easier. However they are big and heavy which is a detriment. For a tow vehicle/work truck pulling a trailer regularly, yes a big block is the way to go. For a light and nimble street car the small block is a better all around choice. Dropping in a big block makes the car into an arrow. Inertia on that mass up front anchors the front and the rest follows.