The fork lift approach was actually that for the rear, high up middle engine. It was apparently straightforward, while the wing engines were specified to need a complex cradle arrangement and more man hours to make a change. One would have thought that the manufacturer would anticipate someone adapting one method to the other, and thinking they were clever doing so. A specific "Never fork lift the wing engine in" instruction was needed. You can also argue that the mounting lugs should have been more robust, anticipating the forces when engines are put in place. A design attitude of "what could go wrong" as well as "what will work right".