I've done a lot of that copying. Here's what I'd do:
1. Remove it from any frame. You've done that already. Never shoot through glass if you can avoid it.
2. Carefully wipe down the print with a soft cloth to remove loose gunk that I guarantee you is on there even if you can't see it. You will see all that crap on your monitor later. So get as much off as you can without scratching the print.
3. Mount the picture as flat as you can on a clean surface. Take it outside, in the shade. The sky makes a nice lightbox with no glare.
4. I use a 50mm lens for minimum distortion. I have a grid etched into my eyepiece to help keep all the sides even when centering the tripod. You may want to use a tape measure from each corner of the picture to the middle of your lens to lessen any distortion. I'd also not fill the frame. That will also lessen any curvature of the edges.
5. Tripod is a must.
6. Even though you're only making 8x10s make sure you edit at 100% in Photoshop. As I said, you'll see all kinds of scratches, dirt, chemical failure in the emulsion, etc. It's amazing how good an old picture will look when you've got the image clean before you print it.
7. One more thought. Make sure you convert to black and white and not try to rely on your printer to print a decent b/w from a color file. I use NIK's Silver Efex Pro2 for b/w conversion but you might have a different method.
Hope I didn't forget anything. Perhaps others can add to this.
