It's difficult to say without looking directly at the situation but if, new custom doors are not an option, you might consider reframing the door opening down to 80" size. With the molding off, remove the jamb and shims. Add a 2x4 and 2 layers of 1/2" plywood to the top of the opening. You will then want to fill in the wall at the top of the opening with steel mesh and plaster or drywall. Apply joint compound, sand and repaint. You may find wide molding or something like a wood sunburst carving that would cover a lot of this. Finally, you can hang new 80" doors in the opening. A recent issue of The Family Handyman magazine had a long article on how to do this. Replace the molding with new.
No, I really don't expect you to do the above. But you might consider trying to sell your old doors to architectural salvage yards to see if you can get anything for them and recover part of the cost for new doors. If I were doing this job, I would strip and refinish the old doors.