Running only water when very cold is a shaky deal. You MUST block off the radiator because it's possible to freeze the rad while the thing is running
I've junked out 3 Mopar engines that were froze due to no antifreeze
One was a commando 273. The heads and intake went onto another engine. This was way back around 76
The other was a 335 hp 383. At first I thought it was OK because the oil looked good. So I got a hose and started filling....and filling.....and filling. I finally stopped an pulled the intake. Block was cracked inside the block valley area.