3.5" bolt circle....so that looks like the flange is the Spicer 211229x/Precision 627 that Nissannut has in his write up and it's what I'm using on an XJ shaft with an adapter to go from that pattern to the TX10.
I hadn't even seen the Shadwolf setup. Basically that same concept that we were using with the ford 1310 flange, but it looks like it's for 1330/1350 flanges so it won't work with the one you linked. You want to look for a Ram or Super Duty CV for that.
Interesting though. You used to be able to pick up the Spicer or Precision flanges for like $60. Now it looks like the Spicer is over $300 everywhere and the Precision isn't even available. That one you linked is a really good price for the whole assembly.