Beetle headlamps fit, but the screw part of the attachment is different. The Beetle bezel has a tab at the bottom for the screw, whereas the Porsche unit has a hole in the bezel itself.
The lenses and gaskets are identical. Top tip - buy VW gaskets to save money.
I looked at a cheaper way of doing the conversion and couldn't find one. Bought a secondhand set of headlamps and refurbished them myself. In retrospect I think I could have put up with the sugar scoops - they're weird and kind of cool, esp if you keep the US indicator lenses and a US-shaped plate.