Update (in case anyone is interested)
I sold the grips, and yes, the buyer was aware of the shinkage. Came across another set, and found they didn't fit either. I figured there was nothing to lose, and heated the grips with a heat gun, just to see what would happen. They dropped right onto the bushings, and fit perfectly. They still look a little small when I compare them side by side with others, but the material expanded enough to return to the original dimensions between the screw holes.
There seems to be some elasticity, because after they were cooled, I removed one to see if it would retain its new size, and it wouldn't go back on the bushings. 10 seconds or so of heat, it expanded again to fit. This time I'll leave them on for a couple days to see if they do it again.
I like these grips, so was pleased to find I could make them useable again.