So you are looking at Ser # 014, N303PM? Not a bad aircraft, it is old and you need to have a good look at the AD's and make darn sure you look at the fine print on the MSP contract.
You get what you pay for and buying one of the oldest 55's flying will come with the associated increase in cost to keep it flying. DOC of a 55 is roughly USD800-1,000 more per hour then a 60 would be.
It all comes down to what the principal wants and how good the guy/girl is looking after an older bird. She is 20 years old and that comes with added costs of operating her.
Others here could possibly advise what big ticket items are due on a 6,600 hour 20-yr old airframe.
Avionics wise, this one has the steam gauges and that also comes with added costs of maintaining them.