you can export the database from the 8.1.6 machine into any machine with any charcter set.
I personally took an export file from Oracle 7.3.4 with charset WE8ISO8859P1 and imported the file into a machine with Oracle 8.0.5 charset IW8ISO8859P8.
You have to remmeber to change the charcter set in the export file according to Oracle's charset table.
Edit the export file in hex editor. The second and the third byte in the file define the character set used for