As far as driveshaft, this web site will give you an idea as to what you will need to do to put in a new one.
http://www.iedls.com/ They also sell them through SummitRacing.com .
I have done a few rear ends. The latest is an early 70's Chevelle / GM 10 bolt in my 1952 Suburban. This one I converted to rear disc ( for about $100.) Last one I did, I solved the parking brake problem with a driveline brake. This one, I will find the proper cables to work with the original brake rod. I know there are a few businesses that custom make cable, plus there are kits you can buy to make your own from the likes of Lokar or Gennie. Don't know if the three speed can be converted, I've always had later model transmissions.
I probably just generated a bunch more questions for you!!!
