That sounds like a really nice idea! I've been looking at the "Rome" series by CNN and BBC and they sure could be done nicelly in the Oblivion engine. Besides being a great serie it has an unique atmosphere that would be very interesting to live in. Just think of all the slavetraders arranging gladiator fights, the cold murderers sneaking up the dark alleys to murder for a piece of bread or the harsh life of a Roman soldier of the 13:th
.
As soon as you set the project up I'm happy to help with what I can, I'm not a moddeler or anything but been looking to learn anyway. (Have been playing around with some 3d-programs earlier.) Besides some Roman lore is easy to get by, it only needs to be applied to the mod.