Are there maintenance records with the coach. Cosmetics are usually also a good indication as to maintenance.
What codes does the generator have, some of the codes are fairly simple to address, others require shop time. Get a manual for the specific generator and learn what the codes are and what might be involved to fix, talk to a repair shop.
What are the tire code dates, what manufacturer?? I had Goodyear on mine when I bought it used. The front was out of alignment so I put new on the front but waited a couple years for the back, changed them when they were 10 years old.
I am not familiar with the engine block issue on the 5.9, was this specific to a SN range. If the engine can be inspected a Cummins shop, have them run diagnostics on it. I did this when I first bought my Windsor, best mahney I ever spent.
The price of the rig is right, if you can overcome these issues I wouldn't hesitate to move forward knowing you may have to commit some money to resolve some of the deficiencies.
2002 Monaco Windsor 38 PKD Cummins ISC 350 8.3L
2005 Jeep Grand Cherokee w/5.7 Hemi