There isn't any complex UVing... it should take about 10mins to fix all the UV and the vertex paint issues. I don't know what you are trying to do that it would take longer than it took to model it in the first place. you've already UVed it, you just have to make a few selections and offset some of those shells. the mesh is capable, turning a corridor into a 4way is probably what everyone would do in that situation.