Hello,
I have done this aswell on a couple in my tank, i couldnt be more happy with the result.
I did a fairly cheap and easy mod, using a 1" coupler, and a 1 "cap for each, nothing is glued.
I tapped the center of the cap and cut the tunze bracket down a bit.
I was also concerned with the cord breaking or cracking.
If you strap the cord to the rotating arm closest to the tunze it will shift the movement to a longer portion of the cable, instead of bending it back and forth on the motor.
You can also drill a second "cord" hole in the coupler or cap,and just run the cord up through the wavy sea, make the hole fairly tight and it will help to tansfer the movement up the cord aswell.
It also makes for a clean look.
This is best drilled at where the coupler and cap meet, so the harness clip from the blue box will still go through.
I made a fairly close mount to the wavy sea, so there was not too much pushing on the arm, and mounted on the center (balance ?) point of the pump so the pivot wasnt huge.
One thing i would love to do to it now, is tap the cap one more time, but on the type of cap that has a domed top.
That way the tunze can be mounted at an up or down angle.
Overall, I give the combination two thumbs up !
Marc.