[O' yeah"74]

I know I'm a newb but I'm at a loss. I purchased my dream car Feb 6th 2013, from my cousin. It's a '74 2.7 rebuilt at Aase Motors in '06. Any ways I just changed the oil for the first time today. Warmed her up came home pulled the oil reservoir plug, drained it things were fine, removed filter, replaced reservoir plug, moved oil bucket under the engine drain plug (center of engine toward the front end). Unscrewed drain plug (17mm) and it released under pressure from spring which also contained a brass tube that was flared on one end and another r small piece (similar to a donut with a groove around the perimeter then flattened). Oil drained from hole as expected but I was NOT expecting any spring assembly. What is this I can't find any info? I have been looking. Did I screw up? After letting all oil drain I reassembled the spring, brass tube and brass donut thingy in what seemed to be logical order and then replaced in bottom of engine. Refilled with BP 20-50. No leaks and thing sound and seem fine except my oil pressure is STILL high 100-120+ ..... I can't figure that out either. Any help would be GREATLY APPRECIATED. Sorry so long.