StickyHydro,
I just happen to have the shop manual for the 1984 Civic/CRX on my desk, and see the following info:
gear 1300-5sp 1500-5sp
1 2.916 2.916
2 1.526 1.764
3 0.960 1.181
4 0.750 0.846
5 0.655 0.714
final 3.473 4.266
So for this year, the CRX (1.5) had a tad taller gearing than the vanilla Civic with the 1.3...I don't have the data for other years unfortunately, but I would assume this would continue.
But overall, 3k sounds about right for 68mph.
Bogatyr