A few thoughts:
The crankcase breather could be a problem (worn reed valve allowing a bit too much venting into the carbs). However, too much oil past the breather could also be caused by more serious problems such as worn rings (compression blowing past the rings, into the case and out the breather).
When I had worn valve guides on my 78 R100S the most noticeable symptom was smoke on deceleration esp. going downhill (cut the throttle and the piston starts sucking through every possible opening such as the valve guides which sucks oil into the compression chamber).
Hard tellin', not knowin'. A compression check is step one.
Keep at it!
Forging ahead, down a false trail.