My 70 SS has been without a Master Cylinder for a number of years...with open lines. Planning a complete brake line replacement with a new MC. Anyone know how big a job this is? Steel lines or Stainless?

If you purchase the new lines all pre-bent from a place like In Line Tube, it should be very easy. Bleeding will be the worst part.

I did it on my '70. I wouldn't call it quick and easy but it's not too bad of a job. Like 70SS540 said, bleeding will probably be the worst part.