A top end overahul is just that - overhaul of the cylinder assemblies, not the bottom end where the rotating bits are. The manufacturer dictates what has to be done to consider the engine overhauled and released for another life period.
If a 2000hr TBO engine had a top end overhaul at 1450hrs then it still has 1450hrs on it and still has 550hrs left until TBO. The log book should reflect this.