Speedmaster spark plug holes improvement??

If someone did nothing more than 318will did, and the only upside to it was it made you feel better....... imo, that’s still “mission accomplished”...... since you’ll stop obsessing about it.

Imo, having a proper valve job done will have a much greater impact on power output than what cleaning up those threads will........ or recessing the holes(which I think is just crazy talk).
Agreed. Proper valve job is first on my list. It should be the minimum anyone does even if they are planning on just "bolting them on".