How do I create a custom report snapshot to use on a dashboard?

Good morning.

A member of my executive team has the Comparative Sales Report Snapshot on his dashboard.  He would like a second version of this report that excludes specific general ledger accounts (such as dividend income) so he can better see our true sales activity.

I thought the easiest way to accomplish this would be to customize the report that underlies the Comparative Sales Report Snapshot and "save as" a new report.  Unfortunately, the new report is not available to add as a Report Snapshot.

After reviewing the on-line help for creating a custom report snapshot, I understand that I need to start my report from a very specific list of NetSuite reports.  How do I know which one of these reports to use as my starting point to retrieve the same information as the Comparative Sales Report that is used for the Report Snapshot?  None of the reports (that I looked at) listed include a data set called "Time" which is used for the existing Report Snapshot.