The problem is a lack of genuine Buddhist material in the West. However, the book 'What the Buddha Taught' by Walpola Rahula is a sound Theravada text that explains that the Buddha rejected the notion of a spirit as opposed to matter. Indeed, the Buddha even described 'thought' as a material phenomenon. The Buddha, like Marx, stated that human suffering is premised upon an inverted mindset that perceives things the wrong way around. The answer to eradicate this inversation and develop a true consciousness. The Buddha defines reality through the Four Noble Truths. This contains the Five Aggregates explanation of reality. The Buddha places the world of matter as being primary, from which emerges sensation, perception, thought formation and consciousness. Consciousness only exists as long as the human sense organs are in regular contact with the physical world. No contact (such as in death) no consciousness. The Buddha also says that when greed, hated and delusion are fully uprooted, then a practitioner realises that there is no rebirth and no divine realms, etc. Trevor Ling has written a number of books about the similarity of Buddhist ideas and Marxist thinking. Marx learned his Buddhism from his friend Karl Koppen (a renowned Early European expert upon the subject) - but his excellent books have yet to be translated from their native German into English. Marx even writes to a friend saying that he had tried Buddhist meditation to help relax his mind:
https://buddhistsocialism.weebly.com/when-karl-marx-practised-buddhism.html
The Soviets appear to have known about this association as Joseph Stalin opened a Buddhist Academic Centre in 1928 as a means to gather and focus good quality work about Buddhist thought. You might be interested in this:
https://thesanghakommune.org/2017/02/21/ussr-fi-shcherbatskoy-1866-1942-expert-in-buddhism/
Best Wishes
Adrian