Or maybe the advice of those you mention is from some oldsters like myself. Can the pump be changed in the car? Sure. But it is usually just a patch on a worn out engine. If you are ok with a patch on a high mileage engine go for it. I'd rather pull the thing get it on a stand and start checking things out to know for certain what I have got. Nothing wrong with spending a couple hours to pull reseal and check everything over. I haven't found a small block with any miles on it that couldn't use a timing chain at a minimum.