Been there done that. Drill out the buggers and replace the screws, not too much trouble. Punch the ends to prevent them from coming out Probably loctite would work too.
regarding studs vs bolts I have 4 studs.
Regarding the carb, look in your FSM and it should have the carb number listed at least in 67 it does. interestingly the 66 and earlier BBD is a bit different than the 67 and later for some of the fast idle / choke linkage etc.
67 Dart 273
View attachment 1715301068
66 and earlier 273
View attachment 1715301069
