We have a set of Edelbrock “bolt-on out-of-the-box” heads on our 410 small block. On the box it says “bolt these right on”, but the factory assembly was terrible, the valve job was sketchy and we had to redo the entire valve job for our own safety before we put them on the engine.
Buyer beware, it doesn’t matter what country they’re made in, it has to do with the quality of the people who are putting it together in the final assembly.