Since Zen is more a methodology than a system of thought, although it certainly does have a system of thought, the self-power of Zen, contains the other power of Pure Land. Once you have self power, you must have other power. After all, the Recitation of the Buddha's name is used as a concentration exercise. This is where Chinese/ Vietnamese Pure Land differs from Japanese forms. The Vietnamese Pure Land adherents also meditate whenever they have the time to, whereas Jodosinshu says that meditation is a mere psychological trick, where you think you are capable of saving yourself. They say we must drop meditation and all thoughts of saving ourselves, and rely only upon Buddha Amitabha to save us. Their practice is to realize exactly who and what they are, without any rosy constructs placed upon their realization.
If your practice is to devoid everything in your mind, does it matter is you use a koan, shikentaza or recreating the Buddha in your mind? All of these techniques work if they are done with great diligence and bring the meditator to the same point, to the satori experience (that is to insight, which Theravadans praise so much.)
When you begin Pure Land practice, you think of the Buddha and his Pure Land as being apart from you. But as you practice it, slowly you come to realize that you and Amitabha are one and the same. You can experience the Pure Land right here and now.