Help with a legacy potato brew recipe?

My mother-in-law came across the following recipe that her late Uncle JuJu used to make decades ago. She passed it onto me in hopes that I could whip up a batch. I'd like to stay as close to the following recipe, but create a real quality product that she and her brothers will both recognize and enjoy.

Here is the original recipe word for word from a scrap of paper from the attic:
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"2 packages yeast
1 can Blue Ribbon malt
3 lbs sugar + 1/2 cup (later)
1 irish potato sliced
5 gal warm water

Mix in churn and let work in warm (not hot) place. When it's almost stopped working add the 1/2 cup sugar and stir well & wait 10 or 15 minutes.

Bottle and seal. Let sit for some days to settle."
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Thoughts? What kind of yeast? Where can I get BR Malt? What is one potato going to do in a batch? I've made three batches of my own brew to date, all extract, and they've turned out great so far, so I'm excited to try this little experiment.

Many thanks for everyone's expertise!

He was surely using bread yeast. I think that it's going to be difficult to stay close to that recipe and make a quality product.