A New Restaurant

Question

A new restaurant opened up locally in a really convenient location and the food looks really good. The restaurant has been operating as a non kosher restaurant for many years. It is owned by 3 Jews and 2 Gentiles. The non kosher restaurant is still open seven days a week. But..... A partition has been set up and a portion of the large kitchen is sealed off to make two separate cooking facilities. Both spaces share the same ownership but are like two completely different restaurants because of the physical separations. There are two separate menus, two distinct sets of utensils and plates in different colors to avoid confusion. (This is from their own promotional article). The "kosher" operation is closed on Shabbat and there is a Mashgiah Temidi who has the sole possession of the keys to the "kosher" restaurants kitchen. I remember once learning that a Jew cannot own a non kosher restaurant and that if he does, then a "kosher" restaurant he owns cannot be considered kosher. (I was taught because of the temptation to use much cheaper taref meat). Was this correct? If I had learned that correctly, does the fact that there is a Mashgiach Temidi change things and make this restaurant kosher? Thanks you.