I'd go to a different testing station. Ask around, find the one most friendly to hot rodders. I worked in a Midas shop in utah back in the late 80's. That place was geared to make money for Midas.And they did emissions testing, everybody got shot down for something or another, just to make money on the repairs. When the say "nobody beats Midas" they really mean it. The customers sure as shootin won't leave there with wallets full of cash. And add more ethanol to your gas. SInce the ethanol subsidies ended, the oil companies have cut back on the ratio of ethanol to gas. Chevron blends it too, just you don't know how much is in there. It wouldn't hurt to add a few gallons of moonshine to up the ratio for the testing. I'm with coolvettes here, the 600DP, (while fine for a 302), is not the carb you want to run in an emissions test. The DP Holley's are race carbs designed to run rich, you want a smog carb to do emissions testing with, that's designed to run lean. Find a Holley 80457 600 to test with.
whenever one of our vehicles fails the test we take it to the "authorized mechanic" and have them do the typical tuneup stuff so that we can say we've 'spent' the money in attempt to pass emissions... after all, it's all just about them getting your money. but geeze, I think 85 and older dont have to be tested, thats crazy they have your mav checked
As was mentioned, find another emissions station, preferably one away from repair facilities. Emissions regulations in general are just another tax. I know some regulation helps as far as clean air is concerned, but the states abuse the crap out of them to get more of your money. If you want proof of that, the extent of the requirements here are the 96 and later "scan and go" tests. Junk that will burn your eyes and make you pass out standing within 10 feet of it will pass emissions and there isn't a safety inspection at all.
Have you done the basic stuff already? Oil change, air filter? Iv eheard old oil can cause problems in testing because the exhaust contaminates it. And the air filter for obvious reasons. I think I read you already did spark plugs and PCV? What is you ignition timing set at? Although it runs great at 10 or more degrees it will run cleaner at 6 degrees. Do the idle setting like mentioned earlier. Set the speed to 1000 and adjust the idle mixture. If you done have a vacuum gauge just do by ear, may have to read up on how to adjust idle mixture on your carb if you dont know how. Ive also had good luck getting my old 347 with iron heads and a decent cam through emmisions doing the things listed above plus adding a gallon of Denatured Alcohol to a half tank or less of gas. this is one of the only alcohols you can buy that is not mixed with water. Its just over $10 a gallon at most home improvement stores. It burns clean and dosnt hurt anything.
