Jack?
When I was doing research for a kit car we built, I ran across some information that indicated 930 CV joints are not only much stronger, but able to take much more ANGLE for load without failure than 911 joints.
I don't recall if there is a difference in flange size (which would be a change) or axles themselves - probably are changes. But if you researched it and found the point valid, and were willing to make the changes - you might reap benefits on your setup over the long run.
Just a random thought from the one of the few chicks who post in the tech forum.
angela