A few questions for clarity.
Do you want more stopping power, the brakes to grab further up on the pedal stroke or both?
Stating that you upgraded to power stops is good but what compound? Brakes are like sand paper. If (for example) Stock was like 250 grit and you "upgraded" to 500 grit, it will take more effort to stop (less friction). Just installing a name brand doesn't mean you have the correct friction material.
Any time you add weight you need to consider upgrading brakes. Larger tires are worse because they add leverage against the caliper. I've added about 600 pounds to my cruiser and several sizes larger on my tires. The pads I went to are super grabby. The next issue was, I eat stock rotors. Upgrade to a stronger rotor and now I'm happy. The down side is, I wear pads out in about 7500 miles. If I wasn't happy, I would need to go to a larger diameter rotor to counter the leverage from the tires.
Next is brake lines. When you stop, a good part of the force is absorbed by the flexible brake lines expanding. The fix for this is Braded brake lines. They almost don't expand. That will make your pedal more sensitive and bring the brake engagement up on the pedal stroke.
Adding a diffrent booster is only the answer if you cant generate enough force in the brake system. That would be the last thing I would mod.
We start with the correct brake material, upgrade the rotors if necessary. If you went with longer brake lines, upgrading to steel braded is necessary or install them for a harder pedal feel. BTW, never buy cheap braded lines. You want the Kevlar reinforced lines only.
Big Brake kits are brutally expensive. If you went to 37's you may consider that. other then that, start simple.
