i'd do the following.
1. now that it's free, remove both cups and clean the shell and cup real well. some would say to tap and face the shell, but i'm cheap and lazy. use boeshield on the inside to clean and prevent rust.
2. reinstall the fixed cup with adhesive (blue locktight) and tighten it like your life depended on it (which it might at that).
3. pack and adjust the bb.
4. commute.
5. if it works, go on a century or two. it it doesn't, use red locktight. i don't like using red locktight on anything, so i'm a bit averse here.

are you sure it's a '76? i have a '76 moto, and its bb is swiss with the left hand thread on the fixed side.