Which proportioning valve should I use??

Which proportioning valve is the correct or safer way for a street car?
Option 1: factory style valve pictured below. It has two lines in, three out. This valve is off of a 79 Plymouth Volare, it was a disk /drum car, but I do not know if it was a power or manual car.

Option 2: run the newer adjustable valve (the bottom picture) in line with the rear brakes only. The concept I believe to work would be run the front brakes with no valve whatsoever, just a T union to split the lines to the left and right, and turn the pressure down on the rear line until the rear brakes stop locking under hard braking.

I am not sure which setup will be the most effective and safest. I hear others saying I need the factory valve because is has an internal valve that give proportionate pressure to the rear, not always a set pressure like I would have in option 2. Any help would be appreciated. Or if somebody could direct me towards some literature on the matter, that would be good as well.