Some of the cart racers around this part of the country will buy the 5hp briggs clones and immediately disassemble them and do a cleanup and decking of the block first. the they use all quality rebuild/racer parts to reassemble them. custom carbs, intakes and exhaust will net them 70-100hp on alcohol.
So if that is possible, a cleanup, good bearing and rings should result in a long running dependable engine. Work, yes but sometimes the fun of it. I've got a 11hp chonda on a factory assembled genset and have been happy so far. except I have to clean up the carb. My fault for not shutting the supply off and running it dry.
Just off the shelf, there are lemons in everything made; cars, guns, dishwashers and even small engines. Bound to happen. but I'm sure frequent early oil changes would help rid the block of machining trash. I read somewhere that someone whom used these regularly would change the oil after an hr, then 2, then 3 until it came out clean and clear which resulted in zero failures of the mechanical sort. A few qts of oil is a cheap investment if it results in longevity.