Delta_G:
That won't make 700 be 0 degrees and 2000 be 180 though. It just sets the minimum and maximum values that Servo will put out. The relationship between angle and pulse length is a property of the particular servo you are using.
It will make write(0) equivalent to writeMicrosconds(700) and write(180) equivalent to writeMicroseconds(2000). That should cover the full range of movement of a servo specified for pulse widths between 700 and 2000 microseconds and that's what the OP seems to be asking for.
You're correct that 0-180 in servo.write() angles don't map to specific physical angles. But given that the full range of movement of a servo could be anywhere from about 110 degrees to about 2500 degrees (for a sail winch servo) it is about the best we can do without individual calibration.
Steve