I would almost bet they come without internals or they will need a complete rebuild and thats $500/carb unless you do it and I didn't want to try the machine work. Basically you have no runners on your manifold with these carbs...if you have exhaust leaks then you will get alot of backfire through the pipe and the carb both.
You also want to make sure what type of webers they are trying to sell you...48IDA's and you have to make sure that they haven't been mangled by some VW guys....they like to bore holes in them for something or other.
Hey I don't have a top either but I drove in the rain
Matt