small cfm 4bbl carb wanted

my son and I are putting a offy 4bbl intake and headers on his slant six Duster but need a rebuild able carb, he is on a budget so needs something reasonable, don't really care if its a Carter or Holley and would perfer something close by to cut down on shipping, we live on Vancouver Island, we would need something in the 350-500 cfm range, we are going with clifford headers with 2" + exhaust and have a mild cam as well but I am not sure if we are using the cam at this point, the carb we find will have a factor on that, thanks:prayer: