My guess would be that having custom doors made would be cheaper and less disruptive than reframing them - unless you think you can do that yourself. (Doing it yourself would save money, but take a lot of time.)
If they're going to be painted, you *could* add 2" to the top and bottom - just glue&nail on some pine, fill with wood filler & sand and paint... I have done that when repairing a door, and it's unnoticeable when it's all painted.
Also, there may be a market for your old doors... Check with antique dealers or post here:
http://www.oldhousejournal.com/swapsandsales/index.shtml