1989 Mazda B2600 estimate for engine rebuild

1989 Mazda B2600 4x4, 150,000 miles. I want to rebuild the engine and have the clutch replaced. There is no major problems with either the engine or clutch; it burns some oil but probably normal amounts for the mileage. What is a ballpark figure that this would cost, and what are the degrees of re-build; do I need to specify certain procedures? What is normally done in a re-build? The rest of the truck is in good shape. Thanks in advance.