When I make a pull/pull setup I make a pulley of whatever diameter I choose then run a pushrod to that pulley from the servo. This takes all of the side load off the servo shaft from the wire tension. You can make them as tight as banjo strings if you want. I use 1 wire that threads through the pulley and wraps around it. I make mine from 3 pieces of plwood (1 center and 2 flanges) then glue them together but for something of this size maybe aluminum would be better. You'll also need to have a shaft to run it on.

carl