"Legacy" implies that there's data in the system. Is there? Under what user?
Is there an application server running? On which host?
Direct Connect was introduced with ArcGIS 9.2, so there's no chance at all
to connect on Oracle's TCP/IP port from an 8.3 client. You'll only be able
to connect via the application server service -- Is it running on the default
port?
I hate to say it , but you're best route to getting data out of your old database
is likely to be through shapefiles. This is bad for many reasons (type conversion,
string truncation, column name truncation, numeric null loss,...), but there isn't
a whole lot of overlap across so vast a chasm of time. You might get lucky with
'sdeexport' files, but modern ArcSDE binaries might have trouble with the level
of conversion necessary to manifest a table in 10.0. ASCII transfer could work,
but I haven't tried to compile against an 8.x library in years, and my tools are
the only ones that could generate the ASCII output with coordinates attached.
- V