Similarly Delta and All Nippon threatened to refit their L-1011s with CF6-80A engines, and if they could have gotten TWA on board, it might have happened. DL and NH both had CF6-powered 767s coming on board 1982-83, so there was a commonality factor to consider.
I would like to know how DL and NH would have accomplished installing CF6's on the L-1011 when Lockheed (the manfacture of the L-1011 by the way) studied the use of CF-6's and found that the engineering requirements were too much to overcome? The CF-6 is longer and lighter than the RB-211 installation would have required new wing pylons, a new S-Duct, a complete redesign of the aft body so the engine mounts could be relocated and the longer engine faired in to the fuselage. In addition to the above use of the CF-6 would redesign of the electrical, hydraulic, fuel and pneumatics systems match up with the CF-6. All that and a complete flight test program to prove the new design airworthy?
Finally, by 1883 the RB-211 was proving its self to be very reliable. It was about that time when DL set a record of having a RB-211 on-wing for 15,000 hours.