I just got a portable Air/Fuel ratio meter from
www.innovatemotorsports.com. I used it to jet my Weber 32/36 last week! It uses a wide band O2 sensor to measure your mixture in real time. You just need to weld in a sensor bung in your exhaust just after the collector(the meter comes with a bung and a plug) This is one of the few affordable meters that's supposed to be really accurate.