Replacing dead drive

[Robert Trevellyan]

it still appears to be 512

You need to look at the ashift property of the pool, not the logical/physical sector size of the disk(s).

I need a "compatible" drive

One of the cool things about ZFS is that any drive that's the same size or larger is "compatible". It's best if you can find a drive with the same or better performance specs, but it isn't necessary.