Mazda Competition (now Mazdaspeed) used to sell "race bearings"...
Guess what they were?
Stock Cosmo bearings...which your 20B already has.
These are the "3 window race bearings" that you see.
I believe Racing Beat sells them as such also?
The only better bearings are the stock FD ones which are "9 hole" bearings and, I believe, deeper groove?
Sorry, I can't recommend anyone for your 20B build.
I do all the work myself.
-Ted