I wouldn't use a leather strap on any camera, especially an older one. Now for the case, sure, you could do that, but that's some thick leather. It won't be easy to do. To me, a case is just something to keep around in the event you sell the camera. I'm pretty sure keeping any camera in one for a lengthy period is not a good idea, especially in a humid climate.
I once threw a leather belt onto the top shelf of a closet in Hawaii. Two months later I remembered that it was there, and it was covered in green stuff. Someplace like Florida or a coastal city would be even worse.