An alternate to grinding the choke is to use a Dubro HD servo arm and grind out the bottom a little so it will sit on the existing arm. Then a small bolt,washer and nut to hold it on. Mine is very solid.

The choke servo under the cowl sounds scary, I'm not even comfortable with them at the front of the canopy. One in the regular tray and cut another opening next to it for the choke.