Depends what you've done to the engine?
Being a 3V the diff ratio is an even taller 2.54:1 than the 4V cars which have 2.73:1.
If you have done cams and head porting etc to lift the power band up then a 2.73 is a good choice.
It would have to be quite radical to make use of the next step which, unfortunately is a big jump to 3.46:1.