It depends if Lufthansa sold the combi kits of these aircraft. If these kits have been sold it's very difficult (expensive) to convert the aircraft from an all passenger configuration in a 7 pallet Combi-configuration again. This 7 pallet configuration is the only certified combi configuration at this moment, with the halon knockdown system installed. The earlier available 13 pallet configuration has not been re-certified after the Heidelberg (SAA- 747 combi) disaster.
If the kits are sold they are in fact dedicated full passenger aircraft, but are still listed as 747-430BC aircraft, with a main deck cargo door and heavier aft floor-beams and a heavier cargo-floor installed and some other small differences.
Note : KLM operates at the moment one 744 combi in all passenger configuration, but still has the kit available for a possible configuration change to the combi configuration. All others 744 combi aircraft are operating in the 7 pallet mode, with the main deck halon fire suppression system installed.
Operating a twin over the ocean, you're always one engine failure from a total emergency.