Some people have asked me to report on the effects of the beisan o-ring replacements.

Full disclosure: I did the o-ring replacements along with sparkplugs, valve cover gasket, air filter changes, oil change about 250 miles ago

Positives
1) car pulls more strongly (torque) on hills / load situations but not hugely so. a slight improvement (say 10% or less)
2) oil consumption has decreased. I used to eat a quart every 1.5k miles or so. This has seemed to gone down (no idea why / VCG not leaking)

Negatives
1) old o-rings were in better shapement than expected so was the valve cover gasket
2) the VANOS head unit bleeds oil and makes a real mess