First off, definately grab a Petronix setup. I have it for the 200 in my 66. I also run the Flamethrower coil from them. I have also heard that the original autolite carbs can be a tad unreliable upon rebuild. I kept mine (as I can never throw anything away) but I have a Holley 1bbl installed right now and it made a world of difference. How do your plugs look? You said your fuel delivery is good - is you fuel filter the original canister type? I just have an inline installed on mine right before the carb and it works great. Nonetheless, it's bound to be something simple.
Keep us posted.
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66 Tahoe Turquoise Coupe
Laser Red 96GT Ragtop
Both are slow but easy on the eyes!