Interesting issue. I have never had one as far apart as you pictured since the pumps seem to almost never have trouble, only occasional leaks. I have never seen them need any of the other seals changed, just the external ones, though of course it is possible for other parts to fail.
Normally they will self bleed with very little effort after refilling fluid and turning the wheel all the way side to side a few times. Do you have another spare pump you could take apart and see how the small parts go together?
Or refer to these pages, fortunately these old style General Motors pumps are extremely common and used in millions and millions of vehicles so there are quite a few DIY pictorials out there for how they come apart and go back together, focused on other makes/models but the same principles will apply. There are lots of youtube videos also. Search for Saginaw power steering pump rebuild.
http://tc.wagoneer.org/2012/08/sagin...p-rebuild.html
https://www.hotrod.com/articles/ccrp...kyard-builder/
https://www.mattsoldcars.com/Restore...n/pspump.shtml
https://www.corvette-restoration.com...-pump-rebuild/