get an AXAS shift indicator, I have one of those, and it's skinny enough to fit perfectly, has four bright LED's that light sequentially between two RPM levels you dial in. RSVersion is selling them for $78 + shipping. that's where I got mine...
The light module is about the size of a 9-volt battery, and the controller is about the size of a pack of cigarettes.
The clock hole is big enough that you could put the shift light and controller together in there, side by side. would look sweet.
Otherwise, I'd add a carbon fiber fill plate, and make holes for engine start button, maybe some swithces for other systems in the car.