Stock jets are 72 in a 3310, I will say at cruise you should not need more than 74 to cure a lean condition.

Make sure your floats are not too low, that can cause a slight lean condition at cruise. There are also other factors like timing. Are you running vacuum advance? If so, with that combo it is not needed. An initial of 17 or 18 and total of 36 should be a good start.