What is the ruling for a person who reverts for the sake of marriage but whole-heartedly accepts Islam and is practicing Islam (i.e. prayers, fasting, Zakah) and making every effort to learn Islam and read and understand the Qur'an?

Praise be to Allah, the Lord of the Worlds; and blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
If this man has become a true Muslim then he is like any other Muslim. He has the same rights and should do the same duties. His entering Islam very late does not have any influence on this rule. But some people might claim to be Muslims just to achieve some objective. So, they show Islam and hide Kufr. But when they study Islam and see how tolerant and good Islam is they choose it as their religion and then become good Muslims. This is why the Prophet (Peace and blessing be upon him) used to deal with the new Muslim in a very special way as to make him love Islam and stick to it.

Allah knows best.