Pretty hard to guess your issues without seeing pictures or more details. Which Scout did you build? Mini or standard? Your motor/ prop combo will work fine on a mini, but too small for the regular one. And, how did you launch your Scout? Taking off from ground or hand launching? However, I will make some wild guesses here.
Since you said you throttled up to 50% to 70% at launch, I guess you were hand launching it. Assuming you we’re flying a regular Scout on three channels, but with a 6” ’aggressive pitch“ CW prop on a thrust angle designed for CCW prop. The natural roll for a plane running CW prop is banking right. To make thing worst, your prop wash is fast but narrow and mostly applies to the left wing due to the reversed thrust angle. So your left wing generates more lift than your right wing (plane banks even more to right) unless you make a very strong toss at launching to overcome the imbalance on lift. So, as soon as your plane left your hand, it banked to the right, people intuitively would reduce throttle and go full left rudder and full up elevator. Unfortunately, your plane did not build up enough speed here, so your tail feathers were not effective enough, and once your plane rolled over 45 degree to the right, your full-up elevator actually became right rudder that turned your plane further to the right, and the left rudder became “up elevator” that increase the AOA of your plane- reduce your speed to below stall speed. Now your plane went into death-spiral. There is no way to recover from that given not enough altitude.
Now talking about the fix. If you would like to use your current setup on a regular Scout. You would need to reverse the trust angle as other suggested, and then try to fly off from the ground instead of hand launching it. As I said your prop wash is strong but narrow so you’d better build up the speed slowly on the ground an let your wing do the work to lift the plane evenly.
good luck!