I don't think the ABEC rating is important. It's a measure of the tolerances and a higher tolerance class doesn't mean that they will last longer. I would just choose bearings from a reputable company. I realize that I recommended "electric motor quality" bearings for the rotor, but really, I...
The spindle bearings are just shielded not sealed (zz but some bearings are just labeled "z" but have shields on boths sides)... they are inboard of separate seals that keep them clean. I think it would be fine to use sealed (RS) type on the spinde though. The added drag is probably miniscule...
The motor rotor has a 6900zz and a 6901z.
The 1st gear shaft and 2nd gear shaft have two 608zz each.
BB spindle has a 6805zz and 6808. Not sure about the needle roller bearing.
EDIT: The needle bearing is 25mm ID x 29mm OD x 17mm (more like 16.6mm since it doesn't have a outer race) long.
I just tore down an EP8 that was making a lot of noise. I found 3 different bearing brands. NTN for the main spindle bearings, NMB for the gear shafts, and LFB (seems to be a Chinese brand) for the motor rotor. It doesn't really matter what brand you replace with, but I would choose higher...