TBO Questions O-200

I'm getting conflicting information, so pitch in to set me straight.

In the archives, I've seen several instances where owners have claimed
taking their O-200's over 3000 hrs before overhaul. I believe that with
regular oil analysis, this could probably be true. HOWEVER, I've seen other
posts hinting that, at annual, the AI may not sign off as airworthy if it's
more than 200 hrs over TBO. What's realistic? (I'm looking at a plane with
good compressions and good oil analysis, but it's right at TBO).

Also, at what year was O-200 TBO increased from 1800 hrs to 2000 hrs? And,
does that increased TBO apply to all the older engines?

Thanks;
Carl