The long and short of it. Not a particularly good design for an advance mechanism. With a fair amount of work a decent curve can be made, but not as good as can be made with a Chrysler mechanism. The rest of it is fine.
If you just want to get things running, it is fine. If you're going to use vacuum advance, try to slow the curve as much as you can around 1800 to 2800. Even if you have to use more initial timing than stock because its hot rodded, the mechanical timing in the 1800 - 2300 rpm range should be similar to factory timing. Otherwise it will ping at moderate throttle when using vacuum advance.
The design issue and possible improvements discussed here.
Modifying YH Advance Weights
I haven't done the major weight modification yet. Your on your own if you try it. Working with a Chrysler built unit at the moment, don't want to mess with Mallory built one since its my fallback and baseline.
Canyoncarver is working with a Mallory YT which is basically the same as the YH
Distributor springs