Well that just throws out the sizing! Well I have three sidedraft carbs that are from a standard 1600 manifold(twon on + one spare) I think that these are the 1 3/4" variety. They alos have the dome tops.

and I also have a pair for smaller sidedrafts that came from a 1000. These are flat top type, and are about 2/3 the size of the other three, which makes them about 1 1/4 inch i guess. Unfortunatly I am at work and cannot view them first hand till next week when I get home. DOH!!!

Well seeing as you cant really have too large a carb, then the only decision is how hard they are to keep tune. The Teech pages here say that they are a set and forget item, whic is ideal!! I plan to get it all dyno tuned anyways when its all done, so that I know what is the best performance and if it drops then I know.