Oil pump priming question

I have rebuilt a dozen LA engines over the last 50 years but I am having a hard time figuring out what this cup plug under the main cap looks like ya'll are discussing . Getting old!
The oil pressure tapping goes all the way down through the engine and out the bottom, with another branch gallery meeting it. There's a small cup plug has to be up in there to separate the two.

Discussion of that area

https://www.forabodiesonly.com/mopar/threads/sb-oil-galley-plug-depth.253707/
https://www.mopardiy.com/mopar-engine-performance-guide-oiling-system/