Did you see the Benfords' papers?
The Benfords (Greg, Jim and Dominic) discussed cost-optimised beacons which would most likely be in line with the Galaxy's plane and shining outwards from towards the Core...
Cost Optimized Interstellar Beacons: METI
Cost Optimized Interstellar Beacons: SETI
...much like what you've described.
