I posted here, one I refinished. Tough paint to remove lotta time in the blast cabinet. The paint has held up well it is tractor paint from Rural King and I just used some of the same red paint for the bumper/grill on an 8n. The paint is holding up well.
https://www.garagejournal.com/forum/threads/what-did-you-do-in-your-garage-today.126997/post-8685394
Now that said
I could use a couple of chains, that are keepers for the screw on caps. So if you got extras you wanna part with pm me!
I spent 20 years maintaining the hydrants in FL where I was a FF/Paramedic. If we found a 'dry' hydrant, we would send the location to the water dept. and they would go out and find out why the hydrant was non-functional. Often it was a broken stem, from some drunk hitting the hydrant and fleeing.
The engine companies were tasked with the hydrant inspections, because the firefighter/paramedics were busy running rescue calls. In a paper I did for a college class, I pulled the records of fires and fire apparatus vs rescue calls (EMS) and it was 14%/86%.
One of the things we did when servicing the hydrants, was to cut the chains. They often impeded the removal of the hydrant port or steamer caps. We didn't have much of a problem with thieves stealing the caps, if the chains were cut.
May have too good of a patina once you wire wheel them. Tells a story and unique. I would contemplate not painting them. After clean up work maybe just a clear coat, if at all.
If your hydrants look like alligator skin, or a pile of potato chips, from the crazed paint multiple layers, don't hesitate to use a 'mule-skinner' side grinder/sander wire cup/brush to remove the crappy paint.
Maybe you want to paint it in a theme. Is your spouse handy with a brush? Etsy probably has many ideas for your spouse.