King pin bearings are most likely 8mm ID, inline skate bearings fit nicely, or have for me. You can buy as much quality as you like with those…
Stub axle bearings are most likely 17mm ID, find an industrial bearing supplier for those. Take an old one with you when you go shopping, and don’t be afraid to get the equivalent size with “seals”, not shields, if you want them to last a long time.
The spacers are kind of unique, they are not plain washers, the little step on one side is there to keep them from dragging on the side of the king pin bearings.
Hope this a little helpful!