This depends a lot on how you take care of it. Treat it nice and maintain it it should last 300k+ miles. Beat the stuffing out of it and it won't last 50k. Most Toyota shortblocks wear really well (especially compared to domestic stuff), you are pretty unlikely to wear the piston bores out significantly. The stuff that will get you is BHGs, oil burning, and replacing everything else bolted to the motor (alternators, fuel pumps, etc). I believe the highest mileage I've seen on a MkII was in the low 400k miles in a wrecking yard. That car had the most oil I've ever seen in an engine compartment, it looked like some dipped it into a crude oil pond a few million times.