I was walking around it for whole day and finally made my mind. I redesign and rebuilt the whole throttle connection. This time I used glass-filled HD servo horn. The benefit of new designs are:
- This arm can withstand heat from the motor,
- It is longer so now full travel is 1 inch.
- because it works at different angle now I have some kind of mechanical expo near the idle. This will give me better precision at low rpm (because it is mechanical on the throttle arm it is not sensitive to the slope on the cable or servo).

I think this is final.

Pictures at idle and full throttle, and from the front.

RysiuM