I believe the hub bore size is 63.4 mm, which is the basically the same as the stock bore size, but I also found that the stock Ford ones were slightly too small.
Since they lost their US distributor, I contacted the factory directly a while back when I wanted to buy one more wheel. This is the contact email address I got off of the Rimstock site, they are the parent company of Team Dynamics-
usasales@rimstock.com