I would cut up beside the center leg seam. Depends on what you want to showcase in your project. Do you want to see the center front seam and pockets on the front of the pants? I would not try to pick out all those stitches. They are stitched too well. Do they still make that funny round patch on the bottom? If you take that off, you would have extra fabric. For the top, I would cut across the shoulder seam and cut out the sleeve. That would give you one large piece of fabric. Those seams will be hard to sew over but it will be a larger piece of fabric, if you need that. Does the flight suit have a waistband? If so I would cut it there and do the same thing.