RE: Engine bogging at 1/4 throttle
I'm not sure you need the original settings. Start by adjusting the high-speed needle valve to where you'd want it at full throttle. Then, go to idle and adjust the low-speed valve. If, as seems likely, this leads to making the low-speed setting leaner, go back to full throttle and you should find that you have to make that a little richer. Etc.