I need a carb

I have had this thing apart maybe 20-25 times,new kit,different folks lookinmg at it and it floods out when you take her down the road. it will idle all day long,tank vented,floats set correctly,used different needle and seat,floats are floating. I have had Mopar heads look at it,nobody can come up with anything,except it is old and non-rebuildable
I had one do that and found the the end of the metering rod was broken off. It still ran ok but the mileage was terrible and it belched out black smoke at anything above idle.