Horizon Flyer
I like Big Pistons do not hold your opinion, since the introduction of the later valve guides ( a lot of years back ) I have not seen a stuck valve in a fixed wing aircraft.
If you are cooking cylinders I would think you are asking too much power from the engine or your instrumentation or cooling is at fault.
Back in the 1970,s a well known flying school at Oxford ran its O-360's bottom end for 4000 hours before overhaul while changing the cylinders at 100 hours.
Most of the problems with light aircraft engines are as a result of under use.
Where do your CHT numbers come from ? I was looking the numbers for the O-235 this week and it said 400F for best engine life, 435F for continuous operation with an never excced of 500F, is the O-360 so diferent from the O-235 ?