Ok, I think I'm just about done with this story.
Through a roundabout way I started looking at different t/c ratios to get the tail ratio of 1.78 and came up with this one:
Aspect ratio 2.5411:1
t/c is 0.393935
Tail ratio is 1.7800
I have tweaked the equation just a fraction to finish curve at 0, I have not done the overlay to the template (still need to work out how), but I think the numbers indicate it is damn close and probably closer than achieved in normal construction errors in scaling.
With an equation greater accuracy is possible by being able to extract data for any point on the curve.
It is just a fraction steeper at the start, then tapers out and curve accelerates again after the 80% mark, though this is pretty much irrelevant in the real world as even the keenest modders will finish their tails around this point.
The analysis of the angles may to some degree be irrelevant as I do not know exactly how the template angles were arrived at.
Below is the 0039 section, again scaled as best as I could on screen
Just edited a couple of little details, minor bugs in spread sheet and adjustment to curve.