I'm pretty sure they're the same. I had a 72 240 one and a 74 260 one out together for a cleanup recently and they looked the same.
I may even have put the 240 one back in the 260. I can check if you like?
I have a spare window for a 240Z if you’re desperate. Rather keep it though as you never know but would help a forum member out over the dust at the garage..!