Kevod HaRav, I pray in a minyan for Minha and we almost never have a shomer Shabbat minyan. I’m Sephardic and the nearest Sephardic shul, other than mine, is a half hour walk. Should I go to the ashkenazi ones, the other Sephardic one, or can I stay?

If a Sephardi davens in a Ashkenazi Shacharit minyan on a Monday or Thursday (longer tachnun), what should he do for tachnun?