No worries. O rings on pv are notorious leakers. Don't fret that. Common leakdown point . Heavy dose of assembly grease will slow but not stop leak for testing but no need to worry about this leak point. Won't hurt anything. Its under positive pressure during engine operation. This is why your pv chamber is full of black oil spooge after engine runs for awhile. Pressure testing should keep a continuous low pressure in crankcase to allow testing of seals and gasket joints. Glycerin leak test liquids are sprayed on suspect areas for testing while under pressure. 5-10 psi is adequate. 15 psi and above can push air past crank seals. Soapy water can be used for external leak test but use care with soapy water inside motor and bearings. Be sure to coat insides with oil first to prevent water from rusting engine bearings or steel parts

 

Is the PV O-ring you’re referring to the one I’ve circled in black in the picture below? Also, is it normal that air passes into the PV areas I’ve also highlighted in black in the second pic (Both on the left and right side of the cylinder) or do I need to remove the small gearing inside that circled PV chamber to get to an O-ring?

 

Yes and yes. The seal from case to cylinder o ring won't hold pressure for more than half a minute. The second picture shows leakage under the cover. Also normal. The o rings are trying to seal a large bore and can't use much surface tension to seal without binding pv at normal (hot) operating temperature. I use regulator to apply constant 5psi and test all leak possibilities with spray of light oil (WD40) and watch for leak. Constant air supply keeps pressure on for test. Most motors leak down past pv in less than a minute unless constant pressure is applied

 

I guess I’ll keep continuous pressure of about 6 psi with a hand pump and will check for leaks around intake, cylinder base/head, case (where gasket mates the case halves) and not worry about air escaping through the right side PV opening on of the cylinder. Thank you