Question for those that swapped a big block into their A body.

Centrifugal superchargers ("snail housing" :) ) tend to be "peaky" because the boost is proportional to the square of the impeller rpm.
Roots blowers are linear but are very heavy, inefficient at high boost levels (sometimes 50% or less) and don't work well with intercooling, and their sheer size can interfere with the driver's line of sight.
Turbos are the best compromise but can be a plumber's nightmare...

Pick your poison.
Sometimes it's just easier to build more displacement.