HI! I wonder what size the tilting servo should have, if tilting a motor with about 19-21 inch prop?
Maybe try to contact firstname.lastname@example.org and see if they stock and provide you an appropriate size one.
Having said that, seems like your aircraft is going to be big enough that a 4+1 QuadPlane configuration might be a better option instead of a tilt rotor; less complication not introducing another possible link of failure.
I was also thinking about 4+1 quad plane as more reliable,with less possible failures.
I have visit foxtech site and the vtols with tilting motors, they have “13” props with 28kg Servo.
So tilting a 19-21 inch prop maybe make big stresses at the tilting servo,atleast over time