So you already have the PB-5?
if so, then as Seapy said, the D700 will mount if you begin in the portrait orientation, mount the D700 and then rotate to landscape orientation.
I got tired of doing that on my cameras(D300 and D800E) so I found a 'sacrificial' extension(PK12 - 14mm) specifically to leave attached to the my bellows(PB-4) to fit the camera with a bit less hassle. Obviously it's removable and hence can be used elsewhere if needed, but I leave my bellows setup connected to the PK12 for ease.
I dare say that the PK13 - 27.5mm may be required to easily mount the D3(due to it's grip). I have a grip for my D800E, which is a bit larger overall than a D3 .. never mounted it that way tho, just the bare D800E on the PK12.
My reasoning for getting the PK12, other than it was cheap! .. is that if I'm going to the trouble to use the PB-4, I'm usually looking for more extension than the PK12(and or PK13) alone, so it's additional extension to the bellows is not so much a disadvantage at all, but in fact an advantage.
If you haven't yet acquired the PB-5, then a PB-6 may be the better option, purely for the D3 .. or the PB-4 due to it's ability to 'tilt/shift' the lens too.
That's why I chose the PB-4 over the PB-6 .. the tilt/shift feature of the front standard.
Note tho that I was very patient in finding the right one at the right price. Took me about 2 years of waiting, searching(mainly ebay, but other second hand stores too, such as KEH) for a very good one to surface at a good price.