How to use Parts Express port ends!!!?

Ok, I'm gettin ready to build my first porter box for a friend. He's wanting to do a 2-2.5 cuft box tuned to 32-34 hz for an older 12 L7. With the box sytle he wants to use, a rectangle port isn't going to be possible. He doesn't want to spend much on his box, so I was looking at this (http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=260-403). My question is, is what could I use to make the rest of the port? would 4" PVC meet up correctly with the end of that port end? I'm also, most likely, going to have to turn the port inside the box, so that it makes an "L" shape, If PVC works, could I just use a 90 depgree elbow to make the turn?