My 66 has factory Kelsey-Hayes. I did mine about 6 years ago with help from some FABO members.
I used the original distribution block. Ran the back brakes through the proportioning valve and bypassed the distribution block.
It's basically what
@pishta recommended.
View attachment 1715420223
At the top you can see where I removed the rear line , capped it at the block and connected it to the line from the proportioning valve.
The bottom line runs to the driver's front. Next on the right runs to the back of the master cylinder. And top right runs over to the passenger front.
Here's my m/c and Summit prop valve.
View attachment 1715420224
