Good evening,
I just stumbled upon this post while looking for Daniel O'rourke peas for the summer.
There are a lot of heritage varieties from Sweden. I think they were pretty good with genbank collections and there are also seed saving organisations like Svenska Sesam where enthusiasts exchange seeds.
A good Swedish pea to recommend is train driver bergfeldts giant pea. It is an unusually large mange tout pea. There are a lot of Swedish heritage peas though since it was an important crop for humans as well as animals in the region.
It sounds like you have the Irish side quite well covered. Perhaps consider to add Gortahork cabbage since it has a potentially intriguing history
https://www.seedsovereignty.info/where-giants-grow/
Life is change and it is arguable constant change that is the authentic experience spanning generations. Not the exact flavour or plant growth of a variety in a specific year. Those moments are as lost as Rutger Hauer's poetic tears in the rain in the movie Blade Runner.
Growing some heritage varieties is a great tradition to have and a great way to remember the past. Best of luck with the project.