Best Way To Repair Butterflies

May 650 Edelbrock carb has holes drilled in the primary butterflies from a previous cam install and now I want to repair them. What's the best way? Rivet, nut and bolt, or silver solder. Maybe epoxy? Of course the best way is just buy new ones but I can't find anyone that sells them.
You people with sharp eyes will see that my port sync is almost closed which is the reason for the repair.DSCN0771.JPG