Code:
(using 8i exp.exe)
exp userid=system/manager file=exp_8_1_7.dmp compress=N log=error.log full=y consistent=y

(using 9i exp.exe)
imp userid=system/manager file=exp_8_1_7.dmp log=error.log full=y ignore=y
Those two should be just fine.

Do you need to precreate anything before importing? As davey23uk allready mentioned, in your case you have to precreate all your tablespaces manualy because you are importing to the same box where the original 8i database exists and you do not want the imp to overwrite your 8i datafiles. Apart from that, imp will take care for everything else.

Give it a try (maybe with show=Y), but this time not with SYSDBA user, use some other "ordinar" user like SYSTEM - I have a feeling your problems have a root cause exeatly at the SYSDBA connection!