All credit for this concept belongs to Armen. He shot me some pics of a similar setup, and all I did was put something similar together a post pics. Enjoy
Katana+GGTS
Parts:
Katana tank/atty
Katana tank cover (optional)
GGTS bottom tube assembly
GGTS telescope (use ss, you wouldn't want to risk stripping the threads on a brass tele)
GGTB battery extension
18650 AW IMR batt
1. Screw shorter threads of GGTS telescope onto where the button of the Katana usually threads on, and then tele onto GGTS bottom tub. Some of the bottom threads on the telescope may still be showing, but don't worry, they'll be covered up.
2. Fully screw the Katana+tele into the GGTS bottom tube so that the two tubes sit flush with each other. In my case, the engravings happened to line up perfectly.
3. Insert your battery into the tube, then, with it in its longest possible configuration, insert the GGTB battery extension. Next, try to screw the Katana atty/tank on, and based on how much room is left in the tank, begin to shorten the length of the battery extension until the tank fits snuggly onto the mod.
It should look something like this
4. Vape!