The cylinder surface must be flat and true to ensure a proper seal. We reference off the crank center-line to ensure the deck is parallel to the crank.
There is simply no way to get your case clean without removing all the gallery plugs. You would be amazed at how much junk we find in some of the blind corners!
The Type 1 based air cooled VW engine has a flawed oil system design that does not allow enough oil to the 1-2 side of the case. The Hoover mods fix this flaw.