Magnum motors are notorious for misfiring without proper spark plug wire routing. There is even a TSB for it. Make sure your wires are routed as the Technical Service Bulletin specifies, check for vacuum leaks, verify engine condition and re-adjust your carb correctly.
Wires don't know what motor they are on. Some wires are not non-conductive enough for high energy coils. If You got the right wires you should be able to run them side by side
