The head sticks out the body, no issues there. Even when the glowplug is leveled below the body linethere will be enough space for the flow to bend off or vortexes to reach the glowplug where with normall horizontal fins and a small tree trunk in the middle it will be much harder to get enough flow to the glowplug.
I left the upper part closed to keap the head more solid but flowing air picked up by the head is now forced to flow through the head and can not bend up. And it gives space for some graphics




Offcource I have no simulation software to get proof of my thinking but when you look at some heads like the MAX engines you can see the fins are with a small angle facing down to the center of the head so airflow is forced down to the glowplug