with the 4 speed I would recommend the 3.23, if you run taller (like 2.76) with the torquey 440 and the 4 speed in a heavy car the clutch will not be happy at all.
I run a 275-70-15 on my stock 440 68 Charger and it is fine on the highway with excellent off the line.
I also have a 68 300 with a stock 440 and 2.76 and it is a highway monster, but off the line is not so happy...