I live in MN, and agree that MCGT is a good resource. Woodbury Math & Science is quite difficult to get into, the waiting lists are very long, so he was lucky to be accepted. One of my older daughter's friends transferred there from her private school at the end of middle school. I asked him about it, and he commented that he liked the course work A LOT, but he did say that there was a lot more drug use than at the school he had come from. I don't think it is an overwhelming problem there, but he did comment on it.
Another good option for high school in the St. Paul Public system is Central High School's IB program; we have friends whose gifted Ds have gone there and had great experiences. One went on to Harvard, and the other to Brown. However, the recommendations for the middle school feeders to it are not as strong (honestly, the black hole of middle school is a problem everywhere...).
