I agree with all the replies here. This is a keeper.
Finding a Merc with 250k that has a good interior is the hard part -- 5 minutes on ebay will confirm that for ya.

Personally, I'd seek a 2nd opinion before I swapped out the IP. There are alot of cheapy possibilities that could be causing a fuel delivery problem (tank screen, filters, etc.).

Look through the papers and make sure it had the "open campaign" exhaust work done (trap oxidizer?). A stealership can also tell you if you give them the VIN. If most of the work was done by a non-dealer, it might not have been done.