Rusty water jackets. Engine sitting for 7 years

I have a friends car whose engine has been sitting for 7 years, in the car. Looks like it was never completely flushed before sitting and now there is probably some rust build up in the jackets. I wanted to hear opinions on filling engine with vinegar for a week and letting it sit and then flushing with water and washing baking soda to neutralize it all or any other better ideas before starting her up