G'day Cameron
I have an LX Torana Front end and brakes in my (unfinished) DRB.
The rear line from the master cylinder goes to the FRONT connector of the proportioning valve. The front line from the master cylinder goes to the rear connector. The switch is in the centre of the proportioning valve on mine.
Brake line from rear of proportioning valve goes to rear brakes, brake line from front connector goes to Right hand front brakes, brake line from bottom of proportioning valve goes to Left hand front brakes.
I made drawings of all the connections when I stripped the LX so I could get them all back in the right places when I put them in the Cobra.
Regards
Garry