This is an exceedingly simple request. Similar to Netherlicious, I am doing my own Nether backport. It will add soul soil and I simply request my block, etfuturum:soul_soul to be checked for as a valid crafting ingredient when that comes out. Netherlicious' soul soil should keep priority if present, however.
Alternatively, I raise the alternative idea of a new OreDictionary tag be created that I could add my block to. If this tag is populated with anything it'll use the 1st entry of that OreDictionary list.

Sure.
How about soulSoil as the oredict?

Works for me. And for the drop you could make it just use the first item in this tag. This should cover any mods that add a soul dirt block in the future. Maybe a soulSand tag too?

Maybe a soulSand tag too?

Good idea. It looks like other mods such as Botania use that oredict, so I'll use it too.