No telling about the true mileage, but if you are correct about the possibilities your chain is in no danger. The only risk to chains in those motors is the plastic rails in the head. We recommend repalcing the rails every 5 years or 100,000 miles. The extent of chain wear can be determined by a precise measure of reatrd of the passenger side cam timing. This must be done as in the shop manual with a dial indicator measuring valve opening against a specification in the TDM (technical data manual). Years agpo when I did more of that stuff, I found that the right cam would retard about 10-12 degrees (to about 10-12 degrees retarded) in about 200,000miles. When I first did this we used to actually correct the timing with offset woodruff keys. Today the labor is too intensive (and costly) so we would just roll in another chain at 200k.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician