Building a Dana 60/pinion offset?

Hi Im building a Dana for my 71 Duster, on Dr. Diffs site axle calculator it said to choose a 1 3/16 pinion offset(std mopar) or a centered pinion. Is there any advantage to center pinion in tunnel? With a centered pinion both axles would be same length, which would make it easier to carry spare axle. Any Thoughts? Thanks
The entire Drive drivetrain is offset. Trust me you won't need a spare...