Carter BBS rebuild.

You can get a marginally passably acceptable carb kit at a parts store. They'll probably have to order it; might take 'em a couple days. Or you can get one at rockauto.com and wait for it in the mail.

But…

…this is the year 2011. The newest A-body is 35 years old. The oldest is 51 years old. Yours is 46 years old. It is a complete freakin' miracle that you can find anything applicable to your car, beyond universals like oil, coolant, and light bulbs, by walking into an auto parts store. And that's without even factoring in the quality issue; finding parts of good quality for old cars almost never happens in local parts stores any more.

That is the unfortunate reality we live in. If you want good quality, correct parts for your ancient car, you will generally have to put up with some inconvenience and deal with the vendors who cater to us.