What we finally ended up doing, in this rough order:
Disassociated all "Attached" parts/Documents.
Used PTC's ChangeTypeSql to get a general idea what columns need to be updated, and to what values.
Queried Oracle to located the correct document in the WTDOCUMENT table.
Stopped the MethodServers.
Backup up the database.
Changed those columns, limited to all iterations of the Document in question.
Restarted the MethodServers
Returned to service.
This appears to have successfully changed a "Reference Document" type object into a "WTDocument" type without any ill effects.
Thanks for the help!
=Don=