lots of interesting replies, never heard of the "California Super", sounds interesting.
I looked at the 50-70 but in addition to it not being a true 50, the case dimensions dictated more than just a finish reamer to lengthen the chamber, the rim is bigger which affects the ejector on the Handis. Even if I had a modified chambering that used a .500 bullet, it wouldn't be a simple hand reamer project like the 357 Maxi was.. oh well, I'll leave it to the wildcatters to iron it out. I figure it's just a matter of time till they do. Then I'll just leach off their work. :-D
thanks,
Ian