There's no value in matching the brand of hubs other than esthetics. IMO, there's very little value in matching wheels or even tires, within reason. Performance wise, it makes the most sense to get the Zipp rear rather than the HED set, though the practical difference would be very very small....
You don't say what your front wheel is, but if longer term you looking to have a set of Zipps, starting with the rear would make sense. Don't forget about changing out brake pads for the CF rim.
If it were me, I'd build up a Pacenti SL23 rim on the PT hub. Slightly deeper, wider, and lighter than the HED rim (I have both).