4swan - The Briess "undermodified" malt still has a Kolbach index of 37, which is "overmodified" by traditional lager malt standards. It's less modified than most malt, but still more modified than I was hoping to find.
Thomas - Low DP is not the reason I'm trying to find poorly modified malt. There are low-DP, highly modified malts, like some British pale malts. I'm looking for malt with a low soluble nitrogen ratio, suitable for traditional decoction mashing.