Re: Increasing flow from reservoir to Explorer pump.
I know this is a long shot, and may not even be possible because I have never looked at it, but do you think it would be possible to swap some accessories around? Can you puts your PS pump down low on the drivers side and move other things around? I believe that if you could get the pump directly below the res, you would alleviate your problems.
If this isn't possible, you might be looking at a custom reservoir. You could cut your PSC res and use parts for it, so all you would need is some alum plate and someone who can TIG very well. If you made it shoe-box looking only smaller with a side outlet that was in small sump and
It could be like the one you posted from Circle Track only laying on it's side and move the cap to the top. You might consider sloping the bottom to make the fluid flow towards the sump. The issue with that design is you could starve the pump again in an off camber situation.
Some ideas google gave my while searching for "Aluminum Power Steering Reservoir"