So, with the 410mm fork, bike facing to the right, seat tube angle is 73.2 and to the left, 73.1
410mm, headtube is 72 and 72.1, again facing east west respectively.
Using my certified accurate fork length adjustment gauge, (a copy of "Field Guide to American Houses") which measures at 30mm, I simulate the length of a 440mm fork, as prescribed by MTBR self proclaimed WTB specialists.
And the results...
The WTB catalog page posted below says the numbers we are looking for are 71-72 head tube and seat tube angles. So actually, my 410 is a wee short, but the 440 would be a wee long, by nearly the same degree error margin, a full degree steeper with the 410 and almost a full degree slacker with the 440.
So what does this all mean? Well, it means that my 410 will still stay, because 72-73 is a very standard frame angle measure, and 70-71 would be pretty slack. It also means that the 410 fork stays because nobody I'm aware of makes an off the rack 425mm fork, which would split the difference between my measurements and give the numbers seen in the catalog. 425mm forks exist, though, for example my AMP F1 measures 420, and my F3 measures 430, with no sag on either counts. It also means that cold weather has come to Florida, and I wimped out on riding this morning, so that I could instead eat eggs, grits and coffee with my family, and play with my tools in the warmth of my house. I am a wimp.