Are you planning to use it as an auxiliary tank for you C? If so where are you going to mount it? Or is it to be used as a replacement? What kind of connection does the tank have on it now? Post a picture of the outlet if you can.
The 1300 has a carburetor so it's much simpler than the ST. One top of that it is a vacuum petcock, but has an actual off position so it could be as simple as a tee in the line and turn off the VTX petcock and run the auxiliary tank until dry then turn on the VTX petcock and run it as normal. That's how I would do it.