The 226 water pumps are not reproduced and need to be rebuilt using your core. They are tricky to rebuild for the casual mechanic without a proper press. Best bet is to go to a known rebuilder. A number of members on FTE have used Cowboy John in Florida with good results. I've got a backup unit ready to head his way.
You'll want to be very careful with the thermostat housing as they are prone to cracking and are also not reproduced.
https://cowboyjohnsautoparts.com/