If it is the lock that's broken, that can be repaired.  Typically, though,
as Cris said, it is the casting itself that breaks, and repairs are not
possible.  He mentioned that he has late model handles, but no earlier ones.
I'm out of handles, too.  I have several lock cylinders, but no castings.
I have successfully modified the later ones for use on the early vans.
Simply cut the tip off the handle with a hacksaw.  Then fill the end with JB
weld, and file smooth after it sets.  Works fine.  Feel free to contact me
should you have questions.
Steve Sandlin
http://www.steveslockshop.com
'84 Wolfsburg Westy
'79 Transporter
'00 New Beetle