Can this car can be converted from manual steering to power steering?

It can if that model that year was available with power steering with the engine you have, but it's a really big job. There's a lot more than bolting on a power steering pump. The steering gear assembly will need to be replaced, you'll need hoses and brackets and the plate the pump bolts to. Pulleys and belts will be different. Alignment settings will typically be different because power steering is meant to make up for the harder steering that results from setting the alignment to make the car more stable at higher speeds. If the alignment isn't readjusted, you'll be able to steer with one finger, and you'll be constantly correcting the direction of travel at highway speeds. That makes for a very miserable car to drive.

You'll want to know of one or two cars in the salvage yards that you can get the parts from. You'll be much better off selling your car and buying what you want.