rings need pressure to seat. the only way to get this is by putting a load on the engine and running it hard, to a point. if the afr's are within reason up to a point you can rag on it all you want up to that point.

the optimal way to do a break in is on the dyno then tune it immediately after. people that fuck up their freshly built engines are those that dont know the afr's and start dogging on it right away. run it lean for just a few minutes and you start fucking things up.