If your going to all this problem why not just machine up and outer stub that access the subaru CV and bolts into the 914 -4 flange, or 911 flange. I would go with the 911 flange, late model with the hub centric pieces on the flange. Strong, OEMs work and you could make it a bolt on affair.
Just me and the odd ideas I have running through my head at times.
You would still need to get the axle lengths set and resplinded.
I would go 944 outer - Dutchman axels and Subbie inner on transide, easily done and repeatable.
You could also use the bolt on adapters for the 930 CV to stock 914 CV flange.
So stock 914 stub on training arm, CV Adapter, 930 CV, Dutchman axle resplinded Subbie CV on trans side.
All that being said I am

and went all 930, so I could find something besides CVs to keep off the road. Which is truly all bolt on.
If history teaches us nothing what will keep me off the road is myself, as when I get the car done, I will tear it apart in short order to fabricate something else.

Now if I can get it recognized as a disorder, I would have the ability to do it when ever I wanted, and just say ..|. .|.. I got it bad, leave me be.
quote the Chili Peppers "I got a bad disease"