John ;

Did this ever get sorted out ? .

Yes , there is always crankcase pressure when the engine is running as the piston moving in and out creates a rapid fluctuation of displaced air , this is normal and is apart from blow by .

Yes , mass volumes of both air and oil will spew out the dipstick hole if you open it with the engine running because the clutch basket and primary drive gear are both right there , running in 1" or so of oil .

My very dim memory of the early , push rod engines tells me some had a nipple on the top of the engine , inside the frame intead of the oil/air separation maze underneath the left side cover , just in front of the drive sprocket on the OHC models .

It's been 10 years since I had a CT200 apart so forgive me if this is wrong but I believe it to be so as the early 50 & 55 CC engines had this too .

Adding a hose to it that curves back over the engine & ends out side , below the engine , stops that nasty oil soaked battery issue those early models had .