I bought an LA 25 the first year. It took a year to break in a tight shaft bearing. Then it ran fine in combat for two more years before the sleeve wore out.
If you can't feel the scratch with a finger tip it's unlikely to have any effect, especially in stunt. A tiny scratch will lose some amount of power, but it won't kill it.
The only alternative is getting it plated, or get a Gardner sleeve.
Another take on LA sleeves. That ^ engine had a bare brass spot below the ports from day one. It ran fine until it wore out. I got a new sleeve. It had a bare spot in exactly the same place.