oggers, let me make it really simple.
YOUR hypothesis is true….until.
The valve temperature "tracks" the EGT, because as the mixture at any given mass airflow is leaned, the EGT goes up AND the CHT goes up. But why does the CHT go up? Because the peak cylinder pressures go up. Just like your air compressor in the garage.
Now at the moment your hypothesis is true right up until the moment they stop tracking each other and diverge. Hypothesis BUSTED. end of argument.
Now when the CHT tracks the valve temp hypothesis is tested in exactly the same way, and it does not diverge, it follows the valve temperature…..what can you make from that? Because when Lycoming did their test with far newer equipment they plotted even better curves showing this in detail. I do not have them at hand, but in several weeks I will be right there in the dyno room and will surely be able to get them, if I remember.
Now just so you know I am not making this stuff up, lets examine what else the NACA had to say about valve temperature. Remember they were not measuring ICP in those days, we can today.
"The effect of spark advance on valve temperature is shown in Fig.9 This figure shows that at a F/A 0.08 the exhaust valve temperature is practically unaffected by variation of the spark advance in a range from 5-25 DBTDC. As the spark was advanced beyond 25DBTDC the valve temperature increased until at 45 DBTDC it was the highest observed in the cylinder".
Hmmmm
If we are intellectually honest with ourselves, we would ask ourselves what also tracks the same by advancing the spark timing. We know today because we can measure what they could not 8o years ago, that the ICP will rise considerably, and funny enough the CHT goes with it. Does that help prove what we are saying??? Thought not.
But wait, there is more…..we know you want more, like this set of steak knives!
In the above while advancing the timing and noting exactly the same results as the NACA were getting we not only got higher ICP tracking with CHT we had a constant decline in EGT.
Yep thats right a decline in EGT!!!! 
Bugger….the timing went up, the ICP went up, the CHT went up,
the VALVE temperature went up and the EGT went down!
Walter…..over to you!