when your going to great lengths to maske sue everything is just so with a build but something like this ring end gap mistake happens, you just have to ask yourself if you want to correct the mistake, or just forget about making the build as good as you can.
it's always easy for people with no vested interest to tell you what you might want to hear. in the end you have to trust your own instincts.
in the end, either the work is correct, or it's not. which one are you willing to accept.
if it were mine, or a customers engine, we'd correct the mistake. and another way to look at it, if we were building it for you and we told you we made a mistake on the rings, would you be okay with it? or would you "expect" us to correct it. if it's the latter of the two, think about it.