An adjustable proportioning valve is often included in kits to balance front to rear braking depending upon your suspension. It is adjustable because every car is different in it's set-up.

If your car has soft springs and worn shocks too much weight can be thrown forward of the cars center of gravity; unloading the rear tires, which first lock up, then skid, causing the rear end to try and pass you. On a lumber wagon it wouldn't be a critical as it is on a marshmallow tough full size car's suspension (it was all about ride quality back in the old days not performance so you could get sea sick in some of these big barges during turns and frequent stops).

Big Dave

 

Thanks for the link. We are thinking about the conversion as well.

 

Hey Big Dave,

Thanks for all the advice and future advice to come! This 67 impala was a gift to me from one of my dad's retired friends. I plan on doing a full engine rebuild on the 327 engine with quality components, new tranny (700r4 i believe), and body work and paint when i can afford it. I'm not an expert and willing to take advice from people! I research anything and everything before applying the idea to the car. By all means, please feel free to leave your advice about a performance engine rebuild, trannys, camshaft systems, etc...Appreciate all the help gents!

Ryan