Malice, when you do this you might have to get brake bias valve plumbed in as its quite often a different pressure sent to the rear if its disks rather than drums, this is often due to differing master cylinders between disc and drum rears brakes. Could solve this completely if you take 16v back axle route, just take take load sensor valve also, so as to avoid rear end lock ups, which are well ropey if it is happening on the foot brake, hence valve. Without this I am pretty sure the rears would lock on any firm application of brake pedal. Not sure if this helps you