So I got the new caliper fittings in the mail yesterday and replaced the old ones. Sure enough, everything now works! My daughter and I went for a test drive going about 40 MPH on a downhill arterial and jammed on the brakes. It felt very solid and at the end of the stop, the rear trailer wheels locked up and we saw some sweet smoke! Definitely better and general driving is great now.
I just finished up cleaning everything up on the routing and securing. I drilled out the rivets and then tapped them to 1/2" and then secured with new SS screws.
So, my conclusion/lesson learned from all this......just stick with normal, auto parts store lines and use the fittings from the brake rotor/caliper supplier. I also recommend the poly line as the main run from actuator to the first tee of the system by the axles.