The torque is a computed torque, not actual. So idling in park it should be close to zero. Not sure about the ratio, unless it's trying to compute the final drive ratio by taking into account tire size, transmission gear and rear end drive ratio.
It goes from the lift pump to the hpfp, then gets pressurized from to about 5000 psi at idle to 25000 psi at higher power settings, you can bet it does heat up, how much I don't know. Don't most duramax trucks have a fuel cooler?
I do know that on Boeing airplanes, the hydraulic fluid only...
Think about it for a minute. With a sump you will have a lot less room for the fuel to move around in. Less likely to slosh out, and rapidly refilled when the fuel sloshes back to the other side. This would only be a concern when close to empty. And when moving at a stable rate, it's the same as...
I would guess then that your fueling is off some. In your tune, if it has overheated enough times I would also suspect head gaskets. Someone else asked earlier about the bypass line for egr cooler, you did add one and not just block it off correct?
You will need to use your harness. From the lb7. Modifications will need to be made. Never done the swap, but a few on here and other forums have. I've seen it recommended to use same year model for swap as it's easier.
Do you have a scanner that will show desired vs actual fuel rail pressure. Make sure your lift pump is actually working. If it is it could be you high pressure pump. It could also be your fuel pressure regulator sticking open, then as it sits slowly closing.