Create a half circular "end room" suitable for a cathedral or throne room

I need a low poly half circular "end" to a room and would like it to look something like this: [login to view URL] (not the throne, just the room). To be clear -only- the end half-circular part is needed, not the entire illustration. It should come in at 30k poly or lower, lower is better. Obviously, it must be more simple, but that's the general idea. It must have a very clean topology and I will pay an extra fee for 2 LOD levels (one half the original and one with barely any detail at all). There is a 10 day deadline on this project - so please only apply if you are able to produce swiftly. This model should be two sided. It will be uploaded into a virtual world and visible from every angle.