I don't think thats an A12 cleaner base though right? I believe it's supposed to be a bathtub? I had a A12 in 1977 or so it was a 410 4spd, but the aircleaner stuff, going by memory, was a big tub with a rubber gasket around it. I do believe the new carbs would be better for you then some old carbs, and also if you can find them, the old DC race metering Jet plates. They are kinda hard/simple to find, but well worth the cost. They will add the extra smile that most lack after they have owned a 6pk for a while. I have owned a few dozen 6pk set ups, built them and tuned them myself. So I am no stranger to this subject. I just don't post a lot.. I have even built the impossible adjustment tool they say you can't make to adjust your carbs without moving the front and back carbs each time for adjustments. But you can use a certain jap made motor cycle carb adjuster tool, cut it here n there, bend it here n there, and it will work like a tool specially designed for the purpose. I live on the words, It can't be done. I don't like hanging around Negative people as it is. Ya just can't advance to the front of the line that way. Good luck with your build....ALAN