In the quest for fine tuning I read...
http://www.fordgarage.com/pages/vacuumtune.htm
...and decided to check my engine. Although my gauge isn't as nice as the one pictured I believe it works good enough. I connected to the windshield wiper port and I get a fast fluctuation between 17 and 21. The fluctuation is present at all rpm's. So to any of you who are experienced in vacuum gauge diagnostics, does this sound like possible valve guide trouble? My primary complaint is loping which I cannot adjust out by the (professionally rebuilt) carb even at a very low (~400rpm) idle.