Ford came out with a new set of IRS half shafts a couple years ago that use the larger Porsche CV joints with their 8.8" center. The axles use a new larger set of stub shafts to accommodate the larger Porsche CV joint, probably similar to what you had to custom manufacture, Scott.
The pic of the stub shafts was too big to put in the thread so here is a link to a pic of the stubs;
https://gforce1320.com/wp-content/up...OR10104A-2.jpg
GForce offers the complete aftermarket package including boots, CV's and axles. While they provide versions for OEM applications they will also make the axle shafts any length you require so they can easily be sized to fit our cars.
Depending on the spline count in your rear drive hubs you may or may not have to have them install different drive splines on the wheel side of the axle.
This is a pic of the complete package including the larger 8.8 stub shafts for the Porsche CV's;
Hope this is helpful for anyone contemplating this sort of upgrade.
Ed