With the higher horsepower motors typically 800-1200 hours would be considered a good/typical service life mechanically before a rebuild.
What isn't known with engines such as this is what is the service life of all the electronic components that actually make it run.
The motor is now 13 years old. How long will the computer and various sensors last. Those can cost more to replace than a total rebuild on a 1980's two stroke.
This IS an early model Opti - if you choose to buy it YOU are the one who will be laying down some of the base line data as to it's performance/issues over time.
If all the "electronics" are original who knows how long they will last.
We can point to numerous 1980-something 150-200's (XR4/XR6 models) and say yes, they will last 30 years with a little work, and in 20 years from now someone will be able to answer the questions you are asking today about the Opti.