is this a good idea
You don’t need shims for the Legacy.
It is already un-responsive, and has a shallow bearing seat so if you do, it’ll most likely unscrew and come apart while spinning.
The KonKave is a good idea.
You can’t put shims in a Legacy, then it will have string slippage.
KK is a good idea.
Check out this thread: kk + legacy + 50/50 string green - Yo-Yo Mods and Maintenance - YoYoExpert
If you do this, you will have a wonderful Legacy. Personally I use a SPEC, and I’ve been throwing this instead of my Dv888, 888, and Skyline for the past two days.