That tiller handle is expensive new. What I have done on some of my old motors that had remote setups was to bolt an aluminum handle/pipe to the "tongue" that the steering connector goes to, the older ones had two holes drilled through them.This is now your tiller,
Then, mount your control box on the gunnel where you can reach it easily, or to a board mounted to the gunnel if you need the box higher, like if you run standing.
This isn't ideal, or quite as easy as a true stock tiller, but works pretty well and you can use it on larger motors, I've seen them on motors up to 115 hp. Just make sure, like with any tiller engine, to adjust the trim tab to cancel the motor torque so the motor doesn't yank to the side if you drop the tiller, thus sending you over the side.