You just need the idle feeds and idle air bleeds threaded to be able to make adjustments. With an old school carb the metering blocks get threaded for a 6-32 x 1/8 brass set screw, the bodies vary but usually the idle air bleeds will go an 8-32 x 3/16 set screw. You can thread the main air bleeds for 6-32 as well, but usually the old school bodies are OK as is with the calibration. If you get the old style carbs and don't want to do that work yourself I can thread both the body and metering blocks, set you up with blank set screws to tune with and a starting calibration. And even billet can be made to look old school...