If the carbs you're using are anything like the older versions, then there would be a hole at the base of the carb for vacuum to operate the power valve. You don't want to block this off. If all you did was bolt on the carbs and didn't use the proper spacer which has a slot in it for allowing vac to reach that hole, it could be all or part of the problem.
Again, if they are similar to the older version, then the jets would be the same as ones from a common 2GC 2bbl rochester. If the local parts stores can't help, then there are several internet places that should have what you need. Just go surfing...
You need to know what you have before you can try changing them. Its usually recommended to go no more than 2 sizes different at a time.
Are you running these carbs all together or are they progressive? How much vac signal at idle?
Are you sure they are all the same size? If progressive, do you still have the idle and power circuits hooked up or are they plugged?
