I have a Ruger 22/45 produced in 1998 with intergral suppresor. Suppresor was built byJohn’s Gun in Texas. Company is now out of business. The suppressor is 9 in long. Is there a company that can recore it and possibly reduce the length? Thanks.

P220Smudge is probably your person. But if this was my quest my first stop would be ecco machine. And if they can't maybe they can tell you who could.
But I'm just putting this out there, I'd be looking at new options as an alternative this is going to be a huge mess of a project.

Ecco Machine indefinitely suspended all services and won't be answering inquiries about it. Everyone is scrambling to pump out cans right now.

I looked around and this guy was suggested. Someone chimed in and said he does good work. Can't tell you anything more than that:
https://riotcontrolweapons.com/services