No, I think that's a separate issue.
Make sure your reservoir lines are running to the correct ports on the Combination valve. They are supposed to only fit one way on Mopar products, seeing as how the line fittings are different.
The C-valve should be oriented with the P-valve part pointing down; that's the end with the added jut-out. Then:
The radiator-side reservoir should go to the rear drum brakes, via the lowest side-port on the C-valve.
The firewall side reservoir should be plumbed to the top-most end-port which should immediately split off to the left and right calipers
I get the feeling your front brakes are not working correctly,if at all. Your pedal, on application, should almost immediately be hard, within about 1 inch of travel. I call this a high,hard,pedal.
We had one fella here, with a Scarebird set-up,
that had an insufficient-front-brake application that he traced to;the M/C did not have enough stroke to properly energize the calipers.
Well if you study that out;It shouldn't be possible unless there is something wrong in the rear system or the pedal-ratio. None-the-less, his solution was a bigger M/C bore with more fluid capacity.
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If you study out the M/C, you will see that while you are pushing the pedal down, you are sliding the front-brake piston down the bore. If the rear brakes are working correctly, then the rear-brake piston will also be sliding down the bore, being pushed along hydraulically,by the brake fluid trapped between the pistons. The front brakes will not be energized until the rear-brake piston stops moving, and has taken up all the slack in the rear slack-adjusters, and the shoes are touching the drums.
Then, with everything now hydraulically locked up, the fluids have no place to go but out towards the calipers and wheel-cylinders. So the pedal gets hard, and that's when pedal-modulation can begin.
Now, if something is mechanically wrong in the rear-brake system, that the piston slides too far down the bore, then the front-brake piston will follow it, also too far. The brake pedal, of course will also fall lower than expected. But finally Hydraulic lock is achieved and braking can begin. But the pedal is nearly on the floor, and there is only a fraction of fluid left in the bore to be pushed out towards the calipers. If there is even the slightest thing wrong in the front system; like the pistons being knocked back, the sliders not working properly,flex in the pads or hoses,or even a tiny pocket of air; then there may be insufficient reserve capacity for the front brakes to be properly energized.
Now if the hydraulic system has failed in the front brake system, or if for some reason the pedal travel is too great; then the front brake piston will travel down the bore until it hits the rear-brake piston, and then, with a very low pedal, the rear brakes can still be modulated . However, the rear brakes do not receive full line-pressure, but only a fraction of it,and the the rear-brake sizing is purposely kept weak to prevent rear-wheel lock-up, so taken together,you have to apply a lot of leg pressure to get any slowing down of the car, which you, the operator, interpret as "poor braking". Very poor.
But..... if you have a high,hard, pedal almost immediately on pedal application....then none of this applies; none of it.
