When we did our chassis car, the driveline was put in 1" to the right. A little extra room for the driver. Desired corner weights and balance easy to achieve with minimal preload or spring manipulation from neutral. It worked well. It wasn't a big power deal. If it is i would want the stuff centered.

Stock floor, stock trans mount, stock K frame, steering, etc, I would put it in factory location. Super Stock Hemis are done that way and they work just fine. The whole engine/trans assembly can be moved back and/or down with some changes to the trans mount, if using motor plates. That would be more beneficial than spending a bunch of effort getting everything in the center. Removable/custom trans tunnel is likely needed to accomplish that. Headers on the left side with stock steering is always a challenge.