Pre-finished bodies are hard to find because they aren't in a high demand. Most people like to paint their own. You could get just about any car body, paint it black and white and have yourself a cop car. As far as the bull bar, You'll want a chassis mounted bumper if you want it to be functional. Not sure if you'll find the look you're going for, but maybe there's a truck bumper that would work if you gave it a little persuasion. Trial and error is one of the best parts of this hobby. Try something out, if it doesn't work, make it work.