A couple of things I'd like to point out:

1. Lifters are in the "oil path,"  they need oil pressure to operate
properly (this is one of the reasons for the chronic "going flat"
problem), and the oil continues on through the lifter up the push rod
and into the heads to lubricate the valve train.  So, if the bores are
worn oil pressure can be low.  It's a rare problem, but possible in an
abused or poorly maintained engine.

2. Put the biggest oil pump in you can get--I have one made by Melling
that works great.

3. Run 20w 50 in anything but a climate or season where is is constantly
below 10 degrees, and then run 15w 40.  The light weight multi viscosity
oils were designed only to improve fuel economy as mandated by the feds
back in the '80s.  In the case of the WBX engine they can be detrimental
because they are physically thinner and won't provide adequate oil
pressure in a worn engine.  The additives supposedly boost the
lubrication effectiveness up to the higher number, but they remain thin,
not what you want in a WBX.  You can even run straight 30w or up to 50w
if you are cruising the desert southwest on a regular basis in the
summer in temps above 80, and your engine will thank you for it.  I run
30w as a break in oil in all my new engines for the first 5000 miles
because of its higher viscosity.

You might as well run this engine for a while, you might get well over
100k out of it!

Stuart