rusty is right. your low oil pressure is from excess clearences,
however.... i would hook up a mechanical gauge to verify oil pressure
before doing anything, you can dump STP or somthing 'thick' but you
will start to get 'deposits' if you use it all the time.
if you determin you are indeed suffering from low oil pressure you can
also change your oil pump to a high volume pump, the gears are 'taller'
thuss moving more oil, you can also change the spring and plunger in
the pump body so that you have more pressure.
the thing to watch (listen) for is bad sounds, if you can hear your
rods and mains when you put the motor under a load you are doomed, and
a wrecking yard bottem end may be in order, you can also take your
existing bottem end to a machine shop and have the crank ground .010
under rods and mains if you do most of the work your self you should be
able to do it for under a hundred bucks.... plus gasgets