Is it a complete engine or just the cylinder your thinking about getting.
ESR does mini sprint engines as well, so by it having a CR250R cylinder on it, it could be a sprint engine that was built some time ago.
A TRX250R bottom end with a CR250R cylinder, was a regular build type of engine for the sprints few years back. Most that I seen around here in the east, had LT Suzuki engines in them & very few used the TRX engines.
Something the sprints do that will really hurt your feelings, when they start the engines, they are pushed & then crammed into gear to start the engine turning over, because they have no clutch parts, all of that has been removed. Man, just think what that transmission is going through every time they start them up.
Neil