any suggestions to get this "glued" back into the block.
What kind of glue?

Looks like its been rtv'd back in once. You might a use light dab of jbweld, but the proper way would be to increase the diameter of the tube. They look like they were a press fit originally. Maybe a tapered rod of some sort. Another option would be to tap the hole and use a brass plumbing fitting. Thats what we do with the late model heads to add the vents.

Just slightly ovalize it and tap it in. Its just a friction fit.