On a Boeing 744 RR RB211 application they have the mother of all lock-out brackets that you can install to 'replace' the integrity of a missing screwjack. Which basically bolts the sleeve to the FWD firewall to prevent deployment in flight. Sorry no gen on the CF6-80. Only other bit of advice I can give is, we once tried to ask GE if we could dispatch a CF6-50 powered 747 with 2 screws of one reverser lockout plate missing and they nearly died...
Brgd's
N1 Vibes