I'm using a mixture of Commodore and Falcon and home made on mine. I have a VU Commodore diff center, AU Falcon uprights and hubs with home built arms. The axles are Commodore and I machined and welded up my Ford axle ends that go into the hubs to take the Commodore 6 ball CV.
I set these up and welded them in the lathe so they run true and then TIG welded them on the inside for extra strength. They only transmit drive forces and not suspension loads so I reckon they are safe.
Doing it again again I'd probably keep the Ford outer CV as is and machine a new axle from 4340 bar stock. Cut the spline on one end to suit the Commodore CV and Ford on the other end. I would then get them heat treated. I've been talking with a heat treating place in Melbourne that do a lot of stuff for the V8 Supercar teams and the prices are very reasonable while the quality is top notch.
At the time when I built this my old Mill and my skills weren't good enough to hob the splines accurately. The new milling machine and the experience making steering shafts mean I reckon could do a respectable job now.
Cheers