XigmaNAS

I had wanted to re-do my NAS4Free set up as a few features did not work as desired. Instead of importing disks from my previous ZFS setup, I went about recreating the configuration as if the disks were new and so I am pretty sure I had overwritten the old ZFS pool to a new ZFS pool. I had used the same name the old ZFS pool was called. Do I have any hope of recovering the old data from the disks? Any guidance would be appreciated.

had used the same name the old ZFS pool was called. Do I have any hope of recovering the old data from the disks?

No, actually not, if you have overwritten the old pool.
In this case, you should just have installed the new OS and import the disks, then go to Disks|ZFS|Configuration|Synchronize
and press synchronize and your pool should be up and running again.

You can try it, but I see very low chances.

what kind of pool was it?

Most likely, your only hope is to let the disks sit for a couple years and check again to see if it can be done.
Did it have any snapshots?

The only way you might recover the data is if you use a data recovery service, which will be in the thousands if not tens of thousands for this.