<VV> Mistery on oil fouled plugs

[Daniel Monasterio]

Several weeks ago, posted about spark plugs fouled with oil, on 1,3 and 5 cylinders. Changed intake valve seals but, problem persisted.Compression was 125 all around, engine is a 140 with 889 cam.After this, I suspected on broken 2nd rings or worn out oil rings so, yesterday took out the power train and removed pistons 1 and 5. No broken rings and all ring end gaps are perfectly within specs.Engine has less than 15,000 miles. Pistons are cast ones with 0.060" overbore, still looking like new. Cylinders still show tiny traces of cris cross honing pattern.Only concern I got this morning is with the upper cover baffle which was trimmed and bolted to the cover, years ago, so, have no way to check if it's openings are on the correct side. Don't have an untrimmedspare one to compare with.. Mine, as it was installed, shows both upper and lower openings to the left side... is it the right placing ?No oil signs on carb balance tube.BTW, never, on 44 years dealing with Corvairs, have had oil fouled plugs, even on high mileage engines.
Have a set of NOS cylinder/piston set and think on installing them after partially milling 0.070" on top of pistons but, not sure if these pistons are good enough for this machining operation.What do you think about ?
As always, thanks in advance for any ideas.
Daniel Monasterio