Q: How to verify if I need a cardone reman rack assembly and a steering gear (complete)?

The parts you have listed are essentially the same part. A "reman steering rack" is a steering rack that has previously been used, but was completely rebuilt/remanufactured to like new specifications. When the term "complete steering gear" is used, that is in reference to the steering rack, and often comes with tie rods and steering boots already installed. The rack itself is what’s referred to as the steering gear. Either of these parts would work, it just depends on what comes installed, quality of parts, and the price. Steering rack replacement should be done by a qualified professional, such as one from YourMechanic.