Couple of things Wayne, have you got a photo of the header when fitted to the car? it could be that it's been dented to provide clearance, perhaps to the steering box? Wouldn't be good to remove the dent and then find you had to re-create it!
Also, I've rebuilt my Quadrajet and am currently fiddling about getting the mixture right (I've got a wideband O2 sensor fitted so I can actually measure what the AFR is). I've actually found the carb to be pretty easy to work on. If you haven't already done so, send an email to Lars Grimsrud at
v8fastcars@msn.com and ask him for a copy of his timing and Q-jet tuning papers, they are both really good. Lars is the acknowledged guru on carbs on the US forum.