If you are considering a bolt on replacement 2 barrell carb then have a look at the Holley 2100. http://carbkitsource.com/carbs/tech/Holley/2100-index.html
If the fix is simple like twisting a screw then I'm more than likely going to keep it until it needs a rebuild. What is the benefits of swapping to a newer carb besides it working properly?
It keeps the haters on the H.A.M.B. happy! As for working properly, my Dad logged a couple hundred thousand miles with one of those and no issues. Here is more information on choke testing, adjustment, and operation: http://www.thecarburetorshop.com/Automaticchokes.htm Jon.