Your are correct, you can remove the Firing Pin Block parts from an standard SP-01 slide and run it on your Shadow frame. It will require that you drive out the Firing Pin Retaining Pin in the slide, remove the FPB plunger and spring, then reinstall the FPRP because it is required to retain the Firing Pin from coming out of the slide.
While this will leave a hole in the underside of the rear of the slide where the FPB plunger was located i have never know it to be an issue.
Edit: Other compatibility issue mentioned below.