Brian,
When you say the right hand link is out of true, are you referring to the main leading link or the reaction link? The main link on the right hand side should be at a slight angle away from the wheel at the front. Try checking that the bore for the wheel spindle nut lines up with the hole for the spindle in the left hand link. If it does, then the link is not bent. The right hand outer support plate for the main mudguard stay should have a joggle in it (between the wheel spindle and the reaction link). Regarding the assembly of the plates and reaction links: I have never understood why Mr Douglas made the sleeves for the reaction links long enough to pass through the side plates. There would have been much less free movement if the short sleeves - as on the Mark 3's - were used, along with side plates with only 7/16" dia holes. The whole assemby could then be clamped up with all the movement confined to the bearing in the end of the reaction links instead of everything turning in the plates that are less than 1/8" thick.
Regards,
Eddie.