I've bought two small used kilns that I want to try and replace the control box to a digital one and I'm not sure what all I would need to actually buy. These kilns are Skutt Electric Kilns the model number is 145, I've found the manual online, the kilns are the same except the plug-ins are different, I'd like to make them the same. Also they say 120/240-208 does this mean I could make it either 120v or 240v, what materials would I need to change them? Could I possibly stack them and wire them together to make one kiln? I'm currently only using a 120v kiln for my work as I don't have heavy duty outlets, the house I live in doesn't have washer or dryer hook ups. Thank you for the help!