| It'll more than likely end up in the sump, but as it's baffled it could well sit there for ever and not get collected by the sump plug magnet.
It could be too heavy to get carried by the oil flow around the sump.
It could end up against the mesh filter??
Before pulling the heads, I'd pull the mesh filter and use one of the magnet tools and have a good "probe" around as far as you can though the sump drain hole and the where the mesh filter comes out of.
There could be a very slim chance that the through way where the head and cylinder meets is small enough to catch the half ring?? They aren't that big and will have an o-ring squashed up in there to. If you could get a magnet down here you may be lucky? | 
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