Oil Filter Canister Blues

[Shoebox]

I am having a heck of a time with something so common, the factory oil filter canister. Finishing my 8ba 276 engine build and I want an original oil filter. I took one I had and just sent it in for chroming,....only to realize upon it's return that it is one that mounts to head bolts, NOT what I wanted and a very expensive mistake (its for sale)! So I pick up another off that auction site and what's with this? See pic. This washer/plate thing at the top of the tube? I am thinking it is a remnant of a deceased oil filter, there are bits at the bottom that seem to indicate this, but boy this thing is really on there. Thought I'd post here before getting rough with removing it. Thanks.