Made it to my hobby shop and came back with the right size servo arms. I'll trim the third one off when I'm done playing.
Came to the conclusion there wasn't enough room within a single bench locker to fit the solenoid and the linkage so...
I moved the solenoid aft and tried a new linkage arrangement. Things were encouraging but there was too much friction for the small solenoid to work.
The medium size solenoid would pull in OK but the spring wasn't strong enough to push it back out. I had set up the linkage to multiply the travel to get the most movement of the valve level I could.
So, I moved the outboard push arm's attachment point out to increase the lever arm as well as moving the forward push arms point inward. Things moved much easier. I get about 50 degrees of throw from the valve's lever so I'm hoping that's enough to find and straddle the "under load" sweet spot. I'm going to "go final" with this concept.
The bad news was I poked a hole in the hull with a file while enlarging holes in the underdecking to position the pivot shaft's blocking. Damn.
Stay tuned.
Landlocked/Ken