Aahh, now I cheated with mine.
I get easily frightened on a long bore of getting it stuck partway and not being able to go either way.
That pump out rigger was bored and the part made to a tad above size.
It was then polished up and retried until it was a slip fit into the housing, this way I know it won't stick. Then it was liberally smeared with Loctite, pressed in and secured with two grub screws from the side.
If had been something like your job i could have secured it by two or three grub screws drilled and tapped half and half into the face of the slug and plate.
John S.