I think the shape is perfect. I like how the handle end droops down so it becomes level when installed.

You probably wont find a stock tiller shaped like that. Usually the handle end points up. Not terrible, but it could be better. The drawing is helpful, and H & L could build one based on that for the non-carpenters here

The worst is a tiller that is too low. Not only do you bang your knee, you end up having to lean over while steering. Becomes uncomfortable

Nice job