If you have maintained regular oil changes with a decent oil and filter,and there's no sign of metal in/on the filter I would keep on enjoying it and not worry.

As stated if its not using any oil everything else imho comes under maintinance and consumables.

You could source another engine and if you wanted to make sure thats ok/replace everything like rings etc..or just get a low miles one.

End of the day do what gives you peace of mind and within your budget.