I had an AONE6 booked in 2001 for 75K base miles; which I never flew due to time conflicts (it was strictly a pleasure trip), not designed to maximize mileage but just to go where I wanted to visit (would be enough to qualify for Emerald on any FF plan). However it was 28 sectors. I suspect you can do 80K under current rules (20 max sectors) with the right routing, but that may not be the best use of an OWE fare (I prefer to use it for high-cost sectors, supplementing other tickets that are for low-cost sectors).