Rear brakes some engage

[boss_hoss]

I'm kinda stumped. I'm running a right stuff detailing big brake kit, and for the life of me I can't get it set up right. When I first got it on the road the pedal was hard and short but the brakes worked fairly well, but not well enough to that I trusted them in an emergency. When I swapped out my rear end I also swapped in a larger 1 1/8" corvette style MC and 9" dual diaphragm booster to try and get a better feel. The pedal feel is better but it doesn't engage the rear brakes enough to stop them when the car is idling in drive when the car is on jack stands. I've tried every bleeding procedure and its flowing plenty of fluid through the lines so I'm not sure where to go next. I rear two things last night and maybe somebody can point me in the right direction.
1. I read that on a Disc/disc set up the lines running from the MC to the combination valve should be reversed. I currently have the lines set up front bowl to front brakes and rear to rear. One article said it should be front to rear and rear to front.

2. Combination valve. I purchased a Disc/disc combination valve but once again an article I found said you needed to remove a hold off valve inside the combo valve to the rear to get the pressures right.

Im probably going to try both this weekend but if anybody can offer some guidance that would be appreciated.

For reference have the following
Right Stuff detailing big brake kit: this kit uses mustang cobra caliper front and rear with the integrated parking brake in the rear. Yes the parking brake is adjusted correctly.
1 1/8" Corvette style MC and 9" dual diaphragm booster
New brake lines front to rear.
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[boss_hoss]

Whoops. Sorry for the title. Too early and not enough coffee.

[boss_hoss]

Well after going through everything and re adjusting the parking brake the pedal went the opposite direction which is the way it was before. Now I have a hard, short brake pedal. Not sure how I'm going to remedy that.

[NOT A TA]

Change clevis pivot location on brake pedal.

[NOT A TA]

Change clevis pivot location on brake pedal, or perhaps smaller master piston size.

[boss_hoss]

Change clevis pivot location on brake pedal, or perhaps smaller master piston size.

Thanks, I was reading up on both of those adjustments. This is the super fun part of the build people don't see. The months of tuning and chasing down bugs all around the car.