All cylinder heads work basically the same way, though a supercharger adds a complicating factor to the equation. The cylinder head's main job is to direct air into and out of the combustion chamber via the ports and valves. A supercharged engine needs a head with a slightly different bias to optimize flow and horsepower.
Generally speaking, n cylinder head's intake ports are far larger than the exhaust ports. The reason for this is pretty simple. The dropping piston creates a few pounds-per-square inch of vacuum, which pulls air and fuel in through the intake valve. After exploding in the combustion chamber, the hot exhaust gases expand and leave it with 10 times or more the pressure than it had when it came in. This means the exhaust ports and valves can be much smaller than the intake while still providing adequate flow.
A supercharger, like a turbo, shoves air into the engine at several pounds per square inch of boost pressure. The extra air combines with the fuel in the chambers and expands, turning into exhaust gases that need to get out as quickly as the new charge come in. If an engine had a vacuum on the exhaust manifold sucking exhaust out, then all would be well. But it doesn't. Instead, the engine needs to utilize much larger exhaust ports to remove spent gases. Hypothetically, a supercharger or turbo pushing 14.7 psi (air pressure at sea level) or more could utilize exhaust ports nearly as large as the intakes.
The same theory holds for intake/exhaust valves as it does for the ports: exhaust flow is a far higher priority than intake flow. If you're building the heads yourself, and are considering larger valves, there is something to be said for keeping your stock intake valve size. Bear in mind that a 2.02-inch intake valve has about 3.2 inches of surface area. If your supercharger is pushing out 20 pounds per square inch of boost, then there's about 64 pounds of pressure trying to force the valve to stay open. This effectively reduces your valve spring rate by the same amount, limiting rpm and necessitating the use of stiffer valve springs.
The Hemispherical combustion chamber is the best design for a supercharged engine. The Hemi allows for quick filling and emptying of the chamber. Its centrally mounted spark plug also gives it excellent octane tolerance, and the pressure tumbles into the chamber instead of simply flowing in. This encourages fuel atomization and an even burn, both of which are crucial for a supercharged engine. One side benefit is that the Hemi head has a fairly low surface-area-to-volume ratio, so more of the heat stays in the combustion chamber, where it belongs.
