ceramic kiln for fusing
Its all about maintaining temperature and the placement of the coils in your kiln. I have done many glass pieces in my enameling kiln, but I have to watch it VERY carefully because it will easily reach 1800 degrees before I know it. The reason that fusing kilns have the coils on the top is because it helps control the fusing process from above your piece rather than along the sides. If the kiln gets too hot, your piece might sag on the sides, but not look fully fused in the center.
Use some scrap glass and play around with it to see how your kiln fires. It may work out just fine or you could end up with a puddle. Good luck!