3/4 cam ... Wow. Have not heard that in a while. The term often led to people thinking they had a 3/4 inch lift cam. Which we know is very likely not the case. For fuel economy on the street I am a fan of the good old Q-jet. Provided you can put around using the small primaries and avoid kicking in the bigger secondaries. Always had trouble with that one myself
Those carbs came stock on engines from 200 to 500 cubes. Trick is tuning it right for your particular application.