xnr:
The reason 'best angle of climb speed' is never published is that there is no regulatory requirement for the speed.
If you can hover OGE with some power margin, your best angle of climb speed is obviously zero, and the angle is infinite. But, if you are unable to hover OGE, then you have a problem. Losing an engine just after lift off, but before Vy (minimum power speed) is also a situation where you would want to know best angle of climb speed. You want to get away from the ground as quickly as possible.
The speed itself is found on the power (vertical axis) vs. airspeed (horizontal axis) diagram by drawing a line down to the right from where the power available touches the zero airspeed point to where it touches the curve of power required.
The problem is that this speed will change with the amount of power available, and you have no idea of what that will be on a day-to-day or flight to flight basis. I would imagine that the amount of change in this speed is not large, probably no more than 5 knots plus or minus the absolute best value.
The number given for Vtoss in the Category A supplement is probably pretty close to this, as the same logic of getting away from the ground applies.
So, thats where it comes from and why its never published.
Hope this helps.