Guess I've never heard of any one who has done that. My first thought was to buy a HARD piece of steel tubing to slide over the existing CV shaft. Cut the CV shaft in halve and then re assemble the shafts into the Hard tube. Then weld up ends of tube to axel shaft(s). OR, find a drive line shop that builds CV axles and ask if they can build one from your dimensions. Jake
Here in Saint Paul Minn, we have a few drive line branches called CLUTCH & U JOINT and they build custom drive line components.... If worse come to worst, call them and see what they can do......
One other thing to consider is, if you try this, the assembly will need to be BALANCED. Those are the options I see right now.....