I had a similar problem on the house I'm re-habbing now.
M-bedroom outer wall bowed out 5 inches. Span 20 feet.
Similar baloon framing.
I decided to install 2x6 collar ties at midpoint of the rafters,
attached with three 1/2 inch carriage bolts on each end.
As I jacked up the ridge, I used a come-along to pull the wall
back into plumb and line. Then installed the collar-ties and cut
out the old ceiling chords. My local building dept said the
engineering was acceptable. The result is a beautiful semi-
vaulted 10 foot ceiling. Makes the room look and feel twice as big
You may consider this option of you don't need the upstairs
A structural ridge would probably solve your problem.
I would recommend a glu-lam beam. The dealer who
sells the beams should be able to engineer the size you
need correctly. This is a major construction project, and
depending on where you live you may want to wait until spring.
Your roof ridge will be open to the elements for a couple of days.
After plumbing up the walls, You will definately need a new
roof almost immediately. As stated earlier, you will have
stress cracks and nail pops everywhere. The roof will no
longer be water-tight.
Master carpenter is a term I've heard in the Northeast.
When I was in the carpenters union, someone told me
that a master was a man with at least 15 years cumulative
experience in several carpentry disciplines.
Don't know if it's true...but it sounded reasonable to me
Anyway, Best of Luck with your project.