Those teeth look rough all the way around, like they have been run against a 12 volt starter gear. If the bolt spacing is the same on the Chevy flywheel and the torus bolts up the same, I see no reason not to do the swap, but be aware that it's possible the Chevy has an oddball spacing on at least one bolt to keep from mis-aligning the ignition timing ball. I'm not sure if that's the case on the GMC.
Jerry
