Seriously, I'd ONLY look at one that is the right price with run-outs. Do the core exchange for factory reman/new engines and treat them right. I knew a guy who bought one with 100 hrs on 2 blue printed engines. He knew his stuff, and within the first 200 hrs, all 12 jugs were replaced.
I hear the Centurion 4.0 is heading for a 400-series STC. In the Duke, they are burning 24-25 gph. Not bad at all.
Essentially do a 100 hour inspection as per the C421 MM. Do a comprehensive AD search. The exhaust section/turbo requires a very close and detailed inspection as well as the bed mounts for the engines.