2L oil pump dilemma

[roccophil at gmail.com (Phil Boeye)]

Engine: 3A block w. JH head (1.8L solid lifter)

Problem: oil pressure too high (by VDO metric gauge)

Actions:

* replaced the OEM 2L pump (36mm gears) with a different 2L pump that had
30mm gears
* oil pressure became even HIGHER and now sets off oil pressure warning
* original pump had 25k on it and was in visually great condition (no
scoring, smooth operation by hand turning - didn't check play)

Now I am concerned.  I was told to install a 1.8L hydraulic oil pump (which
I have since bought).  I had been sent the 2L 30mm pump erroneously some
time ago, so since the 1.8L pump also has 30mm gears, I thought "what is the
difference?".  Apparently there *is* one, I just don't understand it at all.

So I won't swap out the pump until I yank the engine (I think one of the
interior bolts between tranny and pan got crossthreaded - yeah), and this
isn't a regular driver at all.  Now just a 'move it from one spot to
another' kind of car until the fall.  A shame, because this was the one I
drove when I wanted to put my foot in it.

But this really pisses me off.  I cannot tell what the problem is at all and
would appreciate anyone's input on the situation.