I always suggest new foam for the bucket seats to my clients. The old foam shrinks over time, plus it eliminates any damage & funky smells.

For the best fit of your new covers, go with new foam.

Other things to consider if you want to get it all at once;

Seat latches & shims.

Bump stops.

Plastic seat backs.

Rear seat divider panel.

With the seats out, it is also a great time for new carpet if needed.