Subtracting a part from another part (making hole w/casting core)

Greetings -

I have a model of an engine's intake port.  This is a solid model of the airspace in the port (not the walls around the port), as if you had poured foam-rubber into the port, let it solidify, and then pulled it out; it is the shape you would use as part of a casting core.  The part is modelled mostly as a lofted boss, composed of maybe half a dozen cross sections at a variety of non-orthogonal orientations.

I want to create a model of the whole cylinder head.  Rather than tediously recreating each of those cross sections in the cylinder head model and then making a lofted cut, is there an easy way that I can put the two parts in an assembly, and then subtract the port model from the head model to create a hollow intake port?

Thanks...

Mitch

SolidworksAssemblies