I don't know about Tuff Country but when you say they don't make a kit for 1 tons, that means they must not offer u-bolts to fit the 1 ton axles.
The aftermarket lift springs used in 1/2, 3/4 and 1 tons are the same part number depending on the amount of lift and the rear spring length.
There are no "1 ton lift springs" just for a 1 ton. They all share the same springs.
It's only the u-bolts that make the difference with the aftermarket stuff. That and the steering correction parts, too.
You mentioned Tuff Country, you need to simply look for 56" rear springs of your desired lift. If they don't offer any u-bolts for a 1 ton (which I say they do), then you can get them elsewhere.
The 56" rear springs TC will have will fit other variations like the Suburbans and '80 and newer 3/4 ton trucks. All the same part number to fit each other.