The story about it being "Mamie Doud's" limousine is a little hard to believe.
1) Mamie married Dwight Eisenhower in 1916. So she was already Mamie Eisenhower many years before 1950.
2) In 1950, she was an Army General's wife. Now that seems a little unlikely even for a General to be driven in, much less a General's wife.
3) She became First Lady in 1953. Seems unlikely they would have driven her in a 3 year old car.
But it is possible, I suppose.
Nonetheless, if it runs as it says it does, that would be a very nice car.