Torque converter "K" factor is the relationship between the stall speed and the engine torque at that stall speed. Of course, the general rule of thumb says that for a given torque converter, and engine making more torque will exhibit a slightly higher stall speed.

The relationship is: K factor = (stall speed) / (sqrt of torque at stall RPM)

For the factory tune with a K factor of 150, solving for stall speed we get: (150) * (sqrt{283 @ 2000-2600}) = 2500rpm

With the GDE Hot tune, we can guestimate that the engine is about 330lb-ft at the same RPM range. This gives us a theoretical stall speed of: (150) * (sqrt{330}) = 2725rpm

Hopefully this is insightful.