i dont know about the ls9 fitting under the hood of a 944, i mean v8 supercharged, the vette engine bay is much bigger, and gm has designed that engine and sc to work under there, porsche designed it for a 2.5l 4cyl.
i'd say f the ls9 and ls7, go with the conversions that are made for the car.
or if ur really good with mechanics, make ur own.