disassembling Betor shocks

[OhioTed]

Has anyone had experience with disassembly of vintage Betor shocks?  I am working on a pair, but cannot get the top eye-fitting off of the the threaded shaft.  According to this photo from an old shock-rebuild article . . .



. . . a wrench is being used to unthread the shaft.  However, for one thing, the shaft is not notched or beveled at the top for fitment of a wrench.  There is no way to turn the shaft that I can figure out.  

I've actually tried filing two flat sides to the shaft, but even with heavy pressure with wrenches, it still will not unscrew from the eye-fitting - even after days of soaking with PB Blaster, and heating the eye-fitting with a torch.

Any suggestions?  These shocks are in very good condition, and for purposes of authenticity, I would like to reuse them.