Because the Greek spelling is Σεπφωρα, I am pretty sure the π would be pronounced. If the Modern Greek phonetics were being preserved, one would spell it Sepfora. I'm not sure about the stress, but that is how it would roughly be pronounced. From the looks of this: http://www.foundalis.com/lan/grkalpha.htm
it looks like it was quite possible that the φ was pronounced with a P sound as well in Ancient Greek. If that was the case it would be pronounced more like Seppora, which certainly makes it easier for one to connect it to the original Hebrew form.