1966 Barracuda with factory disk: dual master conversion

Hey Guys,

I have a 66 Formula S that already has factory disk brakes. I would like to upgrade my master cylinder to dual chamber. My question is what distribution port to use? The car already has a factory proportioning valve for the rear drums, so I just need a 5-port distribution block.

My current distribution block is 4 port.
1. Master cylinder line
2. Left front line
3. Right front line
4 Rear drum line. (It gets split to left/right at the rear of the car)

So I think I need a similar distribution block, but with two master cylinder input ports.

Does anyone have a part number recommendation?

Thanks!