how much mileage on a 79 turbo before rebuild
 

How much mileage should I expect out of a 79 turbo 3.3 intercooled engine beofre requiring a rebuild?
What would be first to need rebuilding, I suspect exhaust guides and valves, but is 80,000 miles pushing it or should I expect to see more than that.
I assume the short block is fine for 150-200,000 miles.
How about condition of pistons at 80,000? What should I expect for their condition at this mileage?