Depends on the build and rev range. 32/34 maybe would be a good start for a mild unit and up to a 38 for something pretty wicked. I have a number of webers on a shelf in my shop. This is because I went back to S.U.'s. I have found that for me a set of properly built 1.4 or 1.5 S.U. carbs work great.(I have only S.U. carbs on all my race cars and street cars)
I was successful in jetting the webers, in fact folks still bring cars for me to jet. The webers offer a bit more power off idle and off a corner due to having an accelerator pump. The down side is they are very sloppy and always seem to dump fuel out the bowl vent on hard cornering and as a result always smell like leaking fuel. I know folks sell all sorts of devices designed to keep the fuel in the bowl. I have not found any that worked perfectly. This is tough on a rough idling A-series engine.
You can open a can of worms when jetting a weber. There are a number of variables that can get expensive,chokes, emulsion tubes, idle jets and mains. I have a box of chokes, jets, mains and emulsion tubes that all cost money used in search that really good setup. Guys who sell webers for sprites can get you kinda sorta close. They like to sell webers because they know you will likely be buying more parts. It's the gift that keeps on giving. I could get you kinda sorta close but in the end you will either except what someones says will work and try to drive with it or you will end up owning a box of weber chokes, jets, emulsion tubes and idle jets like me.
I own a book about tuning webers. The beginning of the book has very good instructions with graphs and calculations that helped me learn this art. It is still in print and if you read it carefully and do the math you too can get pretty close at first try.
I always try and talk guys out of webers unless of course they came on the car from the factory, then they get to read the book or learn or pay someone like me to do it. It is hard to beat a fresh proper set of S.U. carbs.