Your current carb (Autolite 1100) has a spark control valve that works to control your Load-o-Matic distributor. It does not have centrifugal advance. None of the later larger bore carbs have the spark control valve. Therefore, if you upgrade the carb, you will want to also upgrade your distributor to vacuum/centrifugal advance unit that doesn't need a spark control valve equipped carb. There is a sticky post on this forum that explains how it works.
The best choice would be a Duraspark II unit from a '75 or later 200 or 250. This will also give you electronic ignition and do away with your points.
Or, if don't mind keeping the points distributor, you can use a distributor from a '68-'72 engine. They had vacuum & mechanical advance. You can then throw away your old vacuum line, and use rubber vacuum line from the carb to the nipple on the newer distributor.
Your carb choices include the Carter RBS, the Carter YF, the 1946 Holley, or an Autolite 1100. Another problem is the linkage. All of these carbs were equipped on cars with a throttle cable the pulled from across the valve cover. Some members have adapted them to their original linkage, and others have converted to a cable throttle with an orignal throttle cable bracket from a post 1970 vehicle.
