You have to start with the SR harness, due to the difference in ingnition systems. You will have to lengthen the MAFS wires. As for repinning, you'll have to address the connectors F9 and F10 in the "battery area" as well as the dash connector F2. Since they are available, it's probably easiest to just those connectors off of the KA harness and splice them into the SR one. All of this is thoroughly documented on HeavyThrottle's website in the SR Install FAQ.

It's not hard at all, especially since you have both harnesses. Good Luck!