Here's a little inspiration.
http://www.youtube.com/watch?v=71pUVGYxNkk
I started to make a very disorganized image dump of 2.0L, 2.4L and 2.5L merc powerhead shots, so you can see some of the differences between the blocks and parts.
http://www.wellcraftv20.com/gallery/Mercury_Internals