I have a VMB and I can confirm that undoing those bolts will free the column from the base. It will be very top heavy because the motor is mounted at the top of the column driving the spindle through a long splined shaft. I would recommend that you first lower the head as far as it goes and remove the motor before even trying to loosen the bolts, and take great care as you remove the column that it doesn't topple over. Then you'll have the opportunity to tram the column vertical when you reassemble the machine! I've had my VMB for many years and I'm very happy with it now I've fitted a VFD and 3 phase motor and got rid of the stupid intermediate pulley.