[BrianG]

Thanks all!

I still am not too sure on the motor selector. See if this sounds right to you:

For choosing the motor size (300 vs 540 can, and then S, L, XL) I am using the truck weight:

If weight < 1.5lbs, use the smaller 300/380 size can. (regular Mamba).
If weight between 1.5 and 5 lbs, use an S size
If weight between 5 and 8 lbs, use an L size
If weight between 8 and 16 lbs, use an XL size
If weight between 12 and 25 lbs, use an XXL size (LMT 1950)

I have some weight overlap for the XL and XXL size, but I wonder if there should be some overlap with the others? I know a smaller motor may work on a heavier truck, but this is for an "ideal" setup.

Then, I use the calculated requried kv value to determine the applicable motors which have a kv that falls near that value.