I've never made one, I've just read about them. I would imagine some combination of Pilsner and Munich malt, or maybe Vienna, for an amber or copper colored beer, and old school hops like Hallertau or Saaz. Maybe 20 IBU? Think Bavarian lager, before Helles came around in the 20th century, but with Weizen yeast. The story is that the people brewing for their farmstead or family or little guest house found the yeast easy to maintain, and didn't have the time or ability to make lagers anyway, and that wheat was often considered too necessary for bread so it was forbidden to use it in brewing. There might be recipes somewhere, but I'm sure it was a pretty basic brew, probably SMaSH with local ingredients, maybe even homemade malt. So you'd probably be in the right spirit using whatever you have on hand! I find the idea intriguing too since I'm curious about historical beers, it's always on my "someday I'll get around to it" list but I haven't got there yet.