I use SSSB and my son has Wilwood. I'd prefer Wilwood hands down. It's peculiar that you have so much travel and such a soft pedal, I had a similar situation. I installed a manual prop valve and closed the front circuit off completely then bled the rears and repeated it closing off the rears and bleeding the fronts. I had a bitch of a time with the factory style prop valve but got a perfect bleed and pedal feel doing it as mentioned previously. Wilwood calipers have bleeders in all four corners, top and bottom and should be bled starting at the lowers followed by the uppers. Taping on the caliper lightly releases air bubbles to the top of the caliper where it will bleed out easily. The SSSB system on my car is a whole different animal and required three consecutive bleeds to clear the minute air bubbles out. They use Corvette calipers in their kit (4 piston as well ) and are easy to install. Wilwood requires that you center the caliper and pads to the rotor via spacers and this has to be done near perfectly. If after installation, if Wilwood calipers wiggle the slightest to one side or the other, the alignment of the caliper to the rotor is off and braking greatly reduced accompanied by strange grinding sounds. Neither calipers are of the "slide" design where one pad touches the rotor and the caliper slide sideways until the other pad is in contact. I trashed the master that came with the SSSB kit, it was **** all round, and had to install another brand of a lesser bore but ended up on the threshold of minimum brake fluid volume to the pistons. In the end I installed a Wilwood master and problem solved.
