Gearing ?

Here is a good calculator for the RPM, gear and tire sizing. Speed/Tire/RPM calculator

You need to know what's up with your engine before making too many more decisions. If it is a street/strip car like people tend to title their cars, including myself, they spend way more time on the street than at the strip. Strip time is won by consistency. Forget the ET, that **** is bragging rights and most people lie or their cars don't work on the street. Most guy make "500hp" and run 10's 11's or 12's. Yeah.. whatever...

Me personally I'd set it up to run the RPM you want on the street. There is a little subjectiveness here but general rule of thumb you want to be in the ball park of 2500RPM at 60mph give or take. Let the 1/4 mile nonsense fall where it may. When in doubt go one step taller than you think you want. I.e. in hindsight 4.56's were perfect on paper. 4.30's would have been perfect in real life. You aren't looking to be competitive, you are looking for a timeslip. I can tell just by reading what you wrote.

And FYI you don't cut anything up to install a GVOD. Well, with exception to your wallet, lol. I'd never own another car without an OD of some sort.