An Edelbrock Thunder AVS 650 would be perfect for the car as would a 670 Holley Street Avenger with vacuum secondaries. With a stock engine (heads, cam, valves) you can only get so much air/fuel through the engine (max cfm is fairly low), therefore air flow
velocity becomes more important to your situation. A smaller cfm carb will help keep velocity high and therefore help throttle response.
An article I read years ago mentioned that the factory rating on the 383 AVS was in the 600+/- cfm range but in actuality it flowed more like 450 cfm. The 440 AVS was rated higher but actually flowed around 650 cfm according to the article.
The popular fix to get the 383 running better was to swap to a 440 AVS as the additional air flow helped out.
If I had a stock engine with your gears I'd go for the smaller Thunder AVS carb since I have a soft spot for the AVS carbs. If Holley is your bag then go for the 670 cfm Street Avenger with vacuum secondaries. Either one will give great throttle response and decent fuel economy.
Holley Street Avenger 670 cfm w/vac. sec., elec. choke & secondary quick change kit factory installed $349.99
http://www.jegs.com/p/Holley/Holley-Str ... 9/10002/-1
Additional secondary springs for fine tuning $11.99
http://www.jegs.com/i/Holley/510/20-13/10002/-1
Edelbrock Thunder AVS 650 cfm w/elec. choke $359.99
http://www.jegs.com/i/Edelbrock/350/180 ... tId=752435