All bores will have a taper on the top to allow for assembly (the rings use this as a ramp to the bore). You don't want a gasket that is exactly the same size of the bore. As said above- the gasket's edge (that's exposed to the combustion chamber temps) has to be supported fully by the block and head. That helps it transfer heat into those castings, letting it live. You are right - there's a lot of wasted volume with most common Mopar gaskets. but that's also just the way it is with aftermarket parts. They are made to "fit all xxxx".
