Yes, you can fit the manual safety, but it’s more involved than just swapping the trigger bar. Besides the additional parts (Left paddle, Right paddle, safety detent, detent spring) You’ll need to have the frame cut to accept the safety paddle. AB Prototype offers this service
I wouldn't try converting the FCU, however you CAN build up an FCU for a model with safety, notch an x-5 frame, and put the x-5 slide on it to the best of my knowledge. I've seen at least 1 done up that way.
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