You're welcome! Now you can be our "Dating Dewar's Bottles Expert" !
As for your J&B Rare, this is what we found out: The labelling on this bottle of J&B was introduced in 1974, and was used until about 1987. However, I think the back label is on the earlier side of the date range, so very likely 1970s as suggested.
So, you're right about it being from the '70s!