Replace with Mikunis. That's what all the old folks told me. Had an amal on my 69 bultaco, mikuni on my 74, big difference considering they were both Alpina 350s.
You're supposed to straighten the pan with a ball peen. You know, un dimple it where the bolts pull it in. I do it across the flat on the back of the vise, RTV breaks down and the excess squeezed out floats around in there.
I avoid sealant wherever possible, and RTV above all others.