Solid Lifter Cam

I never hooked up my tach after I went with MSD ignition, but I have the tach adapter, it's hard for me to get under the dash but I need to get it done! I looked at a calculator and it says my 28" tires turned me 3.55's into 3.29's, **** I never thought of that! Looks like I should go with at least 3.91's