In observing the motion of the eccentric strap on my Westbury paddle engine, I see that the center pin takes a sort of oblong path over a full cycle. This is without the reversing mechanism in place. When I attach the lifting link to this pin, that motion causes a slight vertical movement of the lifting link and a resulting slight rotation of the weigh shaft.
Since a reverser will in principle lock the weigh shaft, the lifting link will be constrained to rotate about the end of the weigh shaft arm. What effect should/will this have on the eccentric strap and valve motion? Obviously with two engines 90 degrees out of phase the weigh shaft can't move in two directions simultaneously.