BX23 head DIYer, machinists?

[tshep]

Here are 3 pics of my 3 different combustion areas.
Each seems to have....
A same size line, then a stake point, middle

flute of precombustion chamber?

OR

exactly the same crack.

Assuming these are assembly marks, what is a good homebrew/DIY crack detection method?
Or, not finding any, do I just assume it was the gasket?

I had oh-so-slight bubbling in radiator, 22 years old.

 

[dodge man]

Just a guess the mark is where they are suppose to stake it in?