No adjustment for the brass bushing. I believe the screws you mention are to make minor adjustments as to where the points snap as to the location of the knob on the flywheel. That’s just a guess as I never could see where moving the mech. really made a noticeable difference. I only have Speedsters and Folding Lightweights. They may be of more value on other models. They may be just to hold the point mech. in position. Just tighten the one that’s free. It will move the point mechanism against the other that’s froze.
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.