Edelbrock carb questions

Can anyone tell me, is there any difference between the 1403 and 1404
carbs? (500 CFM electric and manual choke versions.) I know on the
larger carbs the electric choke is the "economy" carb and the manual
choke is the "performance" carb but the info on the Edelbrock web site
seems to indicate that there is not the same difference between the 500
CFM versions. I am this close to ordering a 1404 but am more concerned
with running clean and good throttle response and hopefully acceptable
economy than I am with ultimate power. The reason I am considering the
1404 instead of the 1403 is that I already have all the electric choke
stuff so I don't feel the need to spend the big bucks on it if it makes
no difference.

Also, which would be your pick for a mild 289ci engine (Studebaker,
regular pass. car engine but with an Avanti cam) - a 1403/1404 or a 650
CFM AVS? I have been told that the AVS, even though it is
theoretically way too big for the engine, may actually run better than
the 500 CFM AFB, but I have no experience with the AVS series of
carburetors.

thanks,

nate