In reality that motor is never going pull more than 450 cfm dead stock so 500 is the way I'd go but 6 would be fine also. Go too big and you'll get poor fuel atomization at low rpm - bogging, bad mileage.
Lots of choices here. Anything between 390 and 600 cfm. Those engines have horrible cams, intake manifolds and exhaust manifolds. Anything you do will be an improvement. I think a Holley Economaster or a Quadrajet would be the best choices.
EDELBROCK OR HOLLEY....600 cfm MAX.......
600 cfm. its not a high rpm motor, 600 is more than fine
Something around a 500 would be plenty.
I have a 1979 Bronco (351m), it is dead stock...what cfm of 4-barrel carburetor should I get?
