3.55 or 3.91

Randy's has a nice little calculator http://www.ringpinion.com/Calc_RPM.aspx that will allow you to see what rpm you will be turning at any give speed for different rear end ratios and tire diameters.

If you plan to drive the car 3 or 4 days per week you may want to consider 3.23.

I have 3.55's with a 27" tall tire but I also have an OD tranny so I can run 70 mph on the hiway and be turning just a tick over 2000 rpm. My Dakota pick-up has 3.91's and turns a tick under 2000 rpm at 70 mph but has 31" tall tires.