There is a post with the title "FBGA Device (Messiah/Clone)" on this forum, even containing the humorous ravings of a satisfied customer!
Anyway, yes, it is a Messiah/Clone - a full no swap solution for PAL PS2s including the one you describe.
www.china-messiah.com is the best site for v4 diagrams. The chip is supplied with a comprehensive install guide (for v5) - you would just use the v4 diagrams in conjunction with the guide.
So do e-mail me through my profile so that we can properly carry on this discussion.