bad fuel mileage after rebuild

Hey, people, I recently had a long block rebuild done for my 225/6 in a 66 valiant. Ive put about 600 miles on it, changed out the break-in oil, installed pertronix , replaced the vacuum advance can, had the Holley 1920 rebuilt by a good local carb guy. It idles rough when cold, even with the auto choke engaged. When it gets up to temp it smooths out, but the rough idle returns intermittently when warm. Fuel mileage is terrible--9-10 mpg. When I give it the beans, I can see smoke in my rear view. Power seems up to snuff and timing is set properly. Exhaust has a gassy smell, like incomplete combustion? Suggestions? Thanks, Horace. I forgot to mention it is an automatic.