pretty sure we just used JB Weld in the carb restoration shop I worked in. Clean the parts well, hit em lightly with sandpaper to get nice flat surfaces and it should see very little contact with gas. slather a good amount around the outside of the seam afterward to help. if you can find one of the foam inserts used to put upward pressure on the similar part on Q-Jets you can cut those in half and put them underneath to help also.