Security for Item attribute Group

Content

Team,

We have requirement to define textbook items which have additional attributes ( mandatory ) and will be captured at Master Level. I have created attribute group to capture these additional fields and looking for way to hide these for non-textbook items at Master Org level. One way would be to create a different item class for defining textbook items. I want to understand is there any other way to achieve this and what would be impact of creating a new item class from security and item conversion perspective ?

Thanks in Advance.