Unless you have a master cylinder designed to pump two different volumes, the volumes must match. If the front brakes demand more volume than the rear brakes (or visa versa), the system will not work correctly. The brake cylinder volumes all must match, ie., the rear cylinders capacity is 50cc, then the front must also be 50cc, if one cylinder requires greater than the other, the large volume cylinder will fill at a slower rate and not equal pressures.

Also, their total volume must be less than what the master cylinder can supply or the master cylinder will run out of fluid before pressure is built. I.E., if the master cylinder's total output volume capacity is 1qt, the total volume capacity of all the cylinders combined must be less than (not equal to or more than) 1qt.