Your oil pressure numbers sound good.  Bentley says that 19psi at 2000 rpm
when the engine is warm is the lower limit.  So your engine sounds like it is
within limits.  The pressure sender between the pushrod tubes shouldn't make
the light come on until you are showing a pressure of around 3 psi so
anything higher is OK (10 psi at idle is really about normal).
Your problem still sounds like the warning system to me instead of an actual
oil pressure problem.  The low pressure oil sender should not make the light
blink.  It works like the oil pressure lights of old, it fades on and is on
all the time when the oil pressure is below a certain spec (no blinking).
The other oil pressure sender (near waterpump) should make the light flash
and buzz whenever it comes on.

You could be having a wiring problem or the oil pressure warning system
control board (called the "L" board and located behind the speedo) could be
bad and causing your problems.  I have new "L" boards for $50 if you find you
need one.

So your oil pressure is good your warning system is really the problem.

Hope this helps,
Ken Wilford
http://www.vanagain.com
John 3:16
Phone: (856)-765-1583
Shop:   (856)-327-0027
Fax:     (856)-327-2242