Longhorn Helicopters purchased the 427 simulator from Bell and I believe it is still operational. You can find them right here:
https://www.longhornhelicopters.com
They would be a good place to start. I personally know a few 427 instructors from my time at Bell, however as far as I know there is no access to an actual airframe.
The only operator that I can think of in the US that operates a 427 is the Salt River Project in Arizona (?). I believe they do all their training in house.