Cracks can be easily repaired I think, and old Martins, while the market is fickle, fetch a lot of money (the only reason I have mine still- I would have hawked it in college for beer if I had not realized that very fact). Hard to say without the seeing the cracks and without seeing what it would do, but I have seen them in the asking range from 1K to 3K. Shoot- I found a style 2 a few weeks back in PERFECT condition- guy wants 5k and would not let me play it (it is in an antique store), he wouldn't play it...and I left feeling he was a little crazy, but who knows- he may get it on sentiment.
Heck of a garage find there mate- I kept mine for 20 years before I learned to play it...please don;t do that- lot of joy in the little buggers.