Okay so I am learning and using Andy's B body book for reference.

My application: 72 B body was factory PDB car. Still is but with 73 A body front brakes currently.

Going to First Generation Viper front calipers. Only waiting on pads and bolts from Dodge to hang the calipers.

Per Andy's book So factory front disc pistons are 2.750 " Area is 5.94 square inches

Per Andy's book Viper caliper is 2,520 square mm = 3.91 square inches.

So the area is now 66% of what the area use to be so a decrease of 34% of caliper area.

Currently there are 11 x 2 1/2" drums in the rear of the car. I purchased some 7/8" wheel cylinders to use out back. I see in Andy's book there is no good way to calculate the area of the drum brakes.

Since there are 15/16" wheel cylinders currently and will be replacing them with 7/8" wheel cylinders to reduce the rear bias. This is a decrease of around 7% of area with this wheel cylinder change.

The Power Brake booster and factory master cylinder are going to be replaced with a new 7/8" bore master cylinder in manual mode.

I have 2 questions.

1. How to install the adjustable pushrod for the master cylinder? Any pointers here.

2. Should I plan on an adjustable prop. valve or just see how it works with the factory prop valve?

I would definitely try it first before buying and plumbing the adjuster. You might be pleasantly surprised.

My understanding of the adjustable pushrod is that it should mimic the length and travel of the stock unit.
MOST of the aftermarket Master Cylinders are 2 bolt, while our cars use a 4 bolt arrangement. The 4 to 2 adapter makes up for that, but since it moves the master cyl AWAY from the firewall, the brake pushrod needs to be longer. I would think that if a person buys an adapter, the pushrod should just need to be longer by the thickness of the adapter.
Last month, I monkeyed around for 2 weeks with different parts when I decided to convert my Charger BACK to a non power brake setup. OH what a pain in my rump... WOULD it REALLY have been that much trouble for the factory to put STUDS in the brake pedal cage? Laying upside down under the dash to tighten or loosen nuts in hard to reach areas....AAAHHhhhhh!
Back to the adjustable pushrod: I would expect that it should be long enough to allow the pedal to turn OFF the brake light switch and to reach the end of the travel of the piston inside the master cylinder.

The pushrod doesn't need to be longer when using the MC adapter that I make. The MC adapter is designed the correct thickness to match up the new aluminum master cylinder with the original pushrod.

At least it works that way on a manual brake car. If you're also changing from power to manual at the same time then you'll most likely need to buy a manual brake pushrod.

Find a dirt road and lock them up, see which ones lock first. Under controlled conditions, it will be close to a wet asphalt. Tim

Dirt road?
I guess this is decent advice for those withOUT expensive paint jobs!

I only have 12k invested in my paint job and its not finished yet, I have drivers and come from areas that have dirt roads so I use what is available. A paved road with a light dusting of sand will do the same thing. Tim

Hey... I was just messin around. I used the decomposed granite in front of my shop to test brake action with THIS car.....

I plumbed in a wilwood adjuster and it's wide open, never had to use it.
Viper calipers, bigger truck wheel cylinders...

Thanks for the info. Currently the 11x 2.5 drums have shoes from Firm Feel. So maybe going to the 7/8 wheel cylinder and a less aggressive shoe will be enough to knock down some of the rear bias.

I run front discs (13" PBR) and rear drums. In my setup I needed the prop valve to correct excessive rear bias. I was glad I went ahead and installed it from the start. I am using its full adjustment. I'd like to get 7/8" wheel cylinders so I can back off on valve adjustment. 7/8" cylinders for 11" drums seem hard to find at the AP store. I'd order a set from Rick but I have never been able to get Paypal to work so I get along with the adjustable valve.

Briefly....

> Getting the proportioning spot-on is a real key to reducing stopping distances. All the OEM stuff, '60s/'70s, was a huge compromise.

> Having said that....front disc/rear drum is a moving target. The Duo-Servo brakes (rear drums) are SO non-linear, its crazy.

> Having said that, you can still make a huge improvement over stock with an adjustable valve. Remember: the fronts should always lock first! (Fronts locked = no steering, but car can go straight. Rears locked = SURE spin!)

Rick