The position that you and Walter Atkinson have taken (and as far as I can tell it is an APS thing) is flat out wrong. Let me repeat your position "EGT and exhaust valve temperature are not in any way related". Wrong.
Reading NACA-754 in the context of varying mixture ratio i.e. figure 8 it is hard to see how EGT and valve temperature are not related. Its a pretty strong correlation. Though if you read the entire report it's clear that EGT (more precisely mixture) is not the only variable that effects the temperature of the exhaust valve.
One point that is interesting from the graph in figure 8 though is that for a given EGT when ROP the valve temperature is hotter than LOP.
i.e. at say 1400 degrees LOP results in valve temp of 1200 degrees and 1400 degrees ROP results in a valve temp 1300 degrees. i.e about 100 degrees hotter.