Big Problems with New 408 +PICS

An engine that has been bored and honed oversize with only a few hundred miles on it shouldn't have any ridge. Are you sure the ridge isn't just carbon?

That cylinder would appear to be a little larger but that shouldn't have been a problem if the cylinder finish and ring end gaps were proper. My opinion would be poor ring seating. This may have even gotten better the more miles you put on it. But now that you've taken it apart I'd suggest having it honed at a performance machine shop and if the other rings are OK install new top rings and gap them properly for the type of pistons you have.