Hi,
If you have a sandbox system, then I suggest to install the entire Business Content data flow in 3.x here. Don't migrate anything yet until you have had a chance to document all routines and formulas. Even better, recreate the entire data flow in 7.0 in the development system having a look at the sandbox system.
If you don't have a sandbox (or any other) system where you can do the exercise, then I suggest to delete the entire data flow in the development system (incl. the migrated DataSource) and start all over again. Don't migrate anything yet until you have had a chance to document all routines and formulas.
Last but not least, I am not in favor of installing and using Business Content data flows directly. I consider it as a best practice to create your own InfoProviders (and InfoSources if necessary). This way you can always reference the Business Content data flow. Special attention of course for the DataSource. Once it is migrated, then it cannot be used in a 3.x Business Content data flow. Before migration, please check carefully for any routines and formulas.
Best regards,
Sander