Dual Master Cylinder brake lines?

I did this on my 65 Dart. Lookup my post. Many other posts on this w/ PN's, so use search. Summary (for you to research):

Use existing distribution block for fronts, plug rear port. Use 1/4M-3/16F adapter for port from MC.

New rear tube from MC to in-line coupler to rear tubing.

Adjustable proportioning valve ($25) in series w/ rear line near MC is best.

Don't use residual valve on front disks tube. Don't even need with drums if wheel cyls have "new" style springs ("new" since ~1975).