I am am about to start an engine swap...2.5 in a 2.3. The 2.5 dip stick tube is bent out of repair. Can we put the 2.3 tube in? If so, does it pop out and pop in?

 

Yup, no problem

 

Are you talking to yourself again? Cut that out!

I make the guess that you were able to remove the 'modified' tube and replace it with an unmangled version of the same. The oil level in the pan should stay the same, no matter which pan was installed. Some have cast aluminum, and others stamped steel. Why? Because "we say so." would be a possible answer. I think the cast Al pan was to increase bottom end strength and lower noise, trying to match the Toyo and Nissan engines in competition.
There are always problem spots on engines that I don't like to 'go there'. Dip stick tubes and freeze plugs and 'special' bolts, nuts and washers that just 'happen to have a hole drilled' here or there to allow for oil passage, such as the Vulcan cam gear bolt, or the oil passage on the Lima. Some have a metal 'slug', others don't. And, for those that did, the slug may have fallen to the floor on disassembly, never to be seen again. Just 'grey' areas. I'd rather be doing something else...
tom