Ah, well that's actually easier. If you get any low G tenor set, the pitches are GCEA. If you "rotate" the thinnest string down to the 4th, you'd have aGCE. Just tune them down to your desired pitches and you're there.
If the tension isn't quite what you want, I'd recommend contacting Ken Middleton and get a custom Living Water set. He can select the proper gauges to get you what you want. Or just experiment with stock low G sets to find what works best for you.