Nitpicky an not part of the point, but 900 degrees fareheit isn't 3 times 300.

Absolute zero is negative 459.67 fareheit, so the absolute temps in Rankine (imperial equivalent to Kelvin) are 759.67 and 1359.67, so it's about 1.8 times as hot.

So the problem is you need to cook the turkey at 1820 degrees.