CISA and CISSP: How much do they overlap?

CPA

The CISA and CISSP clearly overlap on security: 30% of CISA is security and CISSP is all security. Will my CISSP study be enough to cover the security portion of the CISA?

Both CISA and CISSP domains cover governance and management of IT, networking, and software development life cycle.

Can anyone who has taken both exams comment on how much they actually overlap?

For my CISSP study I purchased the most recent Shon Harris CISSP text and plan to practice lots of test questions, then finish up with the 11th hour CISSP text. As a side note...any recommendations on the best site for test questions?