I just received e-mail from Dave Kleikamp, one of the original developers of jfsutils for Linux and the only current member of JFS Core Team @ Open source : JFS project Web site
Accordingly to Dave, internal format of AIX JFS filesystem is not compatible with Linux JFS, and therefore direct cross-mounting of drives is impossible. So the drive with JFS filesystem which was created on AIX box could only be read on AIX box
So my course of action now is to recall a RS/6000 43P Model 150 from its 2-years exile in the storage, clean the dust, connect my drives through external SCSI connector (there will be another round of fun adapting 68-pin SCSI of 43P to 50-pin on some of my drives), and either FTP files to Linux box or maybe even try remote mount.
Thanks everyone for your help, it was great fun and I surely learned a lot with your assistance.
Cheers 
Valery