You are going to need to hire a local engineer.
By adding a full second story on a ranch, you are nearly doubling the load to the interior bearing wall.
You will need to investigate that the interior wall is adequate to support the additional load. I've been in many homes of that era in which the framing techniques have been questionable at best. You will also need to reinforce the "center" girder in the basement, probaly need to replace the basement columns or at least add some, and let's not forget about the column footings taht are probably undersized for the current loading assumimg you have footings. They will need to be increased.
I like boo1's suggestion. Assuming you do not have a height restriction, installinhg clear span trusses for the floor and roof eliminates the interior bearing wall reinforcing. The trusses would span from exterior wall to exterior wall. All the additional load would be transferred to the foundation walls, which I am assuming are mortared stone due to the age. The only drawback is that you are adding morew load to the exterior walls which might need to be reimbforced at this point.
Eitrher way you go, you will need to hire a local structural engineer to specify the trusses and review the individual item acapacities.
Good Luck.