If it's available at all, I would look at PJ Motorsports or JetsRus. Beyond that, eBay for a used one. If you can find an IPL for the carb, searching by OEM parts number should help
That screw, and the spring that keeps it from falling out, will come with almost every carb rebuild kit on the market. I have them in stock. Call the shop if you get hung up. www.kenoconnorracing.com