You could also take the valve covers off and make sure the top end doesn't have a lot of surface rust on it. Check turbo's and make sure they spin freely and the impellors aren't touching the housings. Check/drain fuel, change fuel filters, oil and filters, gear oil and filter (if equipped), to start. I'd run them VERY easy the first 10 hours and alternate RPM's, then possibly change the oil and filter again. Check the rack settings and possibly have the injectors rebuilt or at least checked. Then slowly bring them up in rpm's and see what they do. I've seen DD's that have sat a long time and run fine for years and year, I've seen others that have sat a long time and ran like a raped ape for a few dozen hours until they cracked a ring or dropped a valve.