It sounds like you are referring to the grease seal for your new hubs. When installing a seal at the back of a hub the outer part of the seal should be flush with the hub. I have also attached a short video demonstration that you might find helpful.
Then when adjusting the new brake assemblies like the Dexter # 23-26 that you referenced, you will only want a slight but constant drag of the shoes on the drum when the wheel is turned after being properly adjusted. I have again attached a... view full answer...