So, first I was gonna use big ol risers. Then I was gonna use chill plates. Then I kept on reading and I learned about insulated risers. The big deal about the large risers was how much extra metal I would have to melt. They would have to be larger than the area they are feeding. In the case of my gas tanks that would be about a 1 1/2 riser. I don't know for sure yet but I'm thinking the insulated risers could be the same size or smaller than the tank mounting points they would be feeding? They would use extra metal, but if small enough that would be acceptable. One advantage to using a riser over a chill plate I cant get out of my head, is that they would not only help supply liquid metal to the mounting points, but the whole area around where they are located. Then again, I could just be imagining the whole thing. Either way, I want to try both ideas. If they both work great then I'll make my decision based on which one was faster, easier to make, and the amount of metal used to pour the mold.