Our first attempt to resolve the oil pressure problem was this "heavy duty" oil pressure relief valve kit from Bugpack.  
The springs and plungers are accessed by removing very large slotted plugs on the bottom of the engine case.  The theory was that maybe the old ones were sticking or something and we figured a new set couldn't hurt.
    There was no change.
 
    The obvious culprit was the oil pump since we had installed a new one. We had ordered a "heavy duty" oil pump.  The problem is that, depending on who your talking to, a regular oil pump can be 26mm or 30mm.  Or either can be "heavy duty".  Which gets back to my rant in Garage VI.
    Anyway... this picture is kind of misleading because the larger gear is the new-new one that's about to
replace the old-new one that was causing the low oil pressure.  We had replaced our 30mm pump with a 26mm pump.  The smaller one is supposed to be the right pump for this engine, but I think because the engine case has (probably) been line-bored the larger 30mm pump is necessary.

                                                                 OR

    We didn't pay attention to what we removed and ordered the wrong oil pump - DOH!
 
    We made this slick puller to remove the pump with the engine in the car.  I can safely say that this is the preferred method over the "tap & pry" method that was recommended to us.  Actually, it was that "just tap it out with a hammer" (kill your perfectly fine oil pump trying to get it out) method that started this madness.  As you can see, this simple tool can be produced with a piece of square tubing, two carriage
bolts, one eyebolt, and another bolt with the head cut off to make the crosspiece that fits through the eyebolt.  It also helps to put that bolt exactly halfway into a vise, grab a big hammer (known as the BFH in our garage) and then, adopting your best mocking tone, squint intently at the bolt while saying something like, "Excuse me (enter bosses name here)?  Oh I'm in trouble for getting to work late again?  Gee, I'm sooory!"  The BFH will then, almost as if of it's own will, strike that bolt with just the force needed to "change it's attitude" the proper amount.  Or, depending on your work situation, you might need to start over with another bolt!