Good job! Glad you got oil moving up to the rockers. Here's a link to the shop manual you should find helpful. There are some special tools they use here that are going to be hard to find I'm thinking. Maybe some of the other 216 guys (I think there's a 216 social group here on the HAMB) could offer some advice. http://chevy.oldcarmanualproject.com/shop/1949_53/06engine/6_021.HTM Oh, and on adjusting the valves, I adjust them on a running engine but I hear that's old hat now. If you go over to Stovebolt.com and do a search you'll find some easy static adjustment methods. Good luck with the 216, they're great little engines.
You engine has a partical flow oil filter. There is a block where the lines to the filter screw into inside that block is a valve that lets some of the oil to the filter and is then dumped back in the pan. If you loose oil to the rockers or oil pressure when you hook the filter back up check that valve.
Are you talking about the oil distributor plate on the drivers side of the block? The one with the 3 screws holding it down.
That would be the one. When you pluged the line you forced the oil to go to the engine. Probally not the problem but i would check after hookin the filter back up.