Do I need a new engine?

Hi,

I have a 2001 corola with 65,000 miles. The engine consumes lots of motor oil in high speed. The engile also stalls with rattling sound when it is started and in high speed. Except those, the car is operated smoothly.

I brougnt my car to dealer today and they said I need to replace whole engine. That means I need to change blcok short, gasket kit, head cylinder, pump cylinder. Everything. It wiil cost me more than 5,500 bucks. I don't expect I need a new engine.
Do you think it is reasonable? Do I go to other mechanics? Thank you.