Jerry Branch pointed out 50 years ago that "shiny!" is a waste of time, but the customer expects it.
Except to examine symmetry (are the gasket outlines followed accurately? Are all of the left or right-handed ports identical in interior shape? Is the guide exposure the same?), appearance is almost worthless unless you know that the porter has excellent past performance with that casting.
Everything else is just cosmetic.

A CNC program developed for a 906 will do the following on a 518:
1. add 50 hp
2. subtract 50 hp
3. break them
4. no one knows

</rant>