If you offset the engine the spinner wont line up with the cowl corectly for one and it will affect trim but so slight you most likely wouldn't notice

If the t-nuts are epoxied in try using a soldering iron to heat them up before trying to push them out, the heat will soften the epoxy enough to not do to much damage when you knock them
out.
Fill the old holes with the right size wood dowel and drill your new holes
Finish plane,Fly plane, Have fun