The complete index of Lu Xun’s book collection is available: 鲁迅手迹和藏书目录 (北京鲁迅博物馆编，1957); what you want, specifically, is 第三集: 外文藏书目录 (it includes 日文，俄文，and 西文 collections), which has an extensive subsection on Lu Xun’s art collection).
Best,
Anatoly Detwyler <adetwyler@gmail.com>
Postdoctoral Fellow, Center for Humanities and Information
Penn State University