My all-time favorite is a well-tuned 750 Rochester Quadrajet. The tiny little primaries give excellent throttle response and mileage, while the vacuum secondaries produce max power on a 350. Bolt it onto an Edelbrock #7104 Performer RPM Q-Jet intake manifold. Use 1/2" feed line from tank to carb, 1/2" return line carb to tank. Adjust for 5 psi fuel pressure at the carb inlet. If you have no expertise with Q-Jets, have Cliff Ruggles set it up for you according to your particular application.