You don't need alloy strips to mount the top arms securely, I just chopped some plastic off the unused bracket in the FX10 kit and glued it to the inside of the removable front chassis piece (the bit the bumper screws into). Once set I drilled through the now reinforced plastic with 2x 3mm holes and nut and bolted the front arms to there.
With regards to the turnbuckles, the ends are threaded in opposite directions so make sure you pay attention to this as you may be turning one end in the wrong direction. Try gripping the middle with pliers too, that's what I did.