Bearings are 6005, 6204, and 6004. Seals I don't remember sizes offhand but have some at home. Brake side spacer is steel and fine, sprocket side soft alloy. Checkpoint spacers not much better. By my samples, it appears they attempt to fix grooving by undersizing the spacer! The seal lips barely compress on it. Have a shop make you a stainless spacer or cut and press a stainless sleeve on your alloy spacer. I did this and everything lasts really long with normal cleaning and regreasing of seals every couple rides.
Nothing special about the controls and their hardware, it just that 300s vibrate more. I wrap my bars with teflon tape, loctite and snug the bolts down only tight enough so the controls can rotate in a crash and I can rotate them back, but they won't move otherwise.