There may be other things to consider.
I'm just spitballing here but i can see the plug needing some kind of protection.
Now stay with me here. what if there was some kind of Wet Flow situation were fuel would puddle in that area and so they made a hat, so to speak so the fuel rolled on by, instead of puddling. now if you moved the plug out more like toolmanmike suggest......................just thinking out loud here........
No matter what, i would be removing any sharp edge from the combustion chamber!