Oil pump priming question

It's gotta be just the right size, but it's a regular "cup", like a baby freeze plug, that is installed from the rear main end of the block and it bottoms out about 1/2 way to the oil pressure sending unit next to the distributor.

It should come out for proper cleaning and needs to be installed so oil pressure won't be bled off to where it shouldn't be going to. There is a Direct Connection/Mopar Performance diagram out there showing the details.