What Disc Brakes to Use

Yeah just when you thought all disc brake questions had been answered (LOL).

I need some help. I have just completed a Hemi Dart clone and it screams but it does not stop. Stopping is important. I was in a rush to put the car together and used a kit from ECI not becuase they were cheap, which they were, but becuase it was available quickly . Bolted right on to my 10 inch spindles and looked like it would do the job. Anyway...it uses Chevy calipers and to be honest the 10 inch drum system worked better than this disc setup. Called ECI and asked for their opinion on probemls and all I got was a run around...it's this and it's that...ect. I have replaced the master 3x times with new ones not rebuilt parts...the rear brakes are 11 inch off a b body, new lines and all new brake parts...installed a SSB prop valve in the rear line, new hoses...basicaly new everything and the car just will not stop.
I used the 11 inch rear drum brakes becuase bigger is always better right? or did I miss soemthing?

I am going to trash the ECI kit. My question is before I spend more money chasing problems and parts that do not work together I want to spend the money on something that will work. Throwing gobs of money at a problem does not always solve it.

I have a complete disc setup from a 75 Dart sport, upper and lower control arms...calipers rotors, ect...basiclly everything. Will this setup stop the car? What else do I have to change to make this work? I know I have to replace the UCA (big ball joint) what about the LCA? If I change the LCA what ball joints do I use the ones for a 68 Dart or the ones for a 75 Dart Sport? The 75 Dart parts also place the caliper on the front of the rotor...good or bad?

Would it be better to use a Wilwood or SSB kit as opposed to the 75 Dart parts? Should I trash the 11 inch rear brakes and replace with 10 inch drums?

The car is a blast to drive with a 680 HP Hemi but when it comes time to apply the whooooaaa pedal...life gets interesting...

I work in Iraq and Afghanistan so I only get a few months at home each year and would rather spend my time grabbing gears and listening to the sweet sound of a high RPM Hemi rather than chasing brake parts that do not work.

There are a lot of smart Mopar folks on this site and I am sure someone has the answer. Thanks guys.