A '77 might have come with a 14" vent. If so, I think that you can identify the lids by looking at the hinge style - I've seen websites that sell the replacement lids that show the various hinge styles so that you can choose the right one.
If you have a 9" Hehr (metal) or Elixir (plastic) vent, then your choices are limited: Hehr no longer makes that vent, and the Elixir vents are not very high quality. In that case you may want to do as mentioned and go to a 14" vent.
If your '77 does have a 14" vent, I still wouldn't think you could be sure of brand by comparing with other Bolers. I say that because I have a feeling that different plants (or even the same ones) probably used different parts at different times. And/or it may have been replaced. So I would look at what you have and go from there.
PS: I keep seeing the thread title
and then thinking "What about the other 74 questions?"