The clue to solving this is in the MEL. If you fly an NG you will notice that N2 guages are not mentioned-so they are both required for dispatch. The old base check curly one was to fail the eng. one N2 guage on taxi out (after dispatch and now into the QRH)-the survivors of this were the ones who called engineering BEFORE takeoff-the others well......
On the basis that AC lies and DC dies the pulling of the CB MUST be an option before shutting down an engine. Also remember that the manual gear extension door in the flight deck is monitored if the contact is "open" the gear will not retract-a good stamp on it during the "rainbow" check will buy some insurance.