Engine swap?

Your wife's car should have a small hub converter and I underline should, a 68 and later slant will bolt up ok as long as you install a bushing in the rear of the 68 and later crank. You will need to reuse the early A oil pan and pickup tube. A lot of things happen to a 60-year-old car. You know the engine has been replaced at some point in its life but many of its secrets won't be known until you remove it and find them. There are members here that sell the bushing as far as the oil pan crawl under the car and have someone turn the steering against the steering stops and observe if the drag link clears the oil pan ok, if not you may need an oil pan and pick up tube. The tubes are no longer available new so used is about the only option.