I'm waiting for some books on the subject and will do more research if I do this but I'm curious if the keel needs work and I need to replace ribs is it best to flip the boat and then do the repair on both ribs and keel from the bottom? Thanks for any help!
Not knowing anything else about your project and - admittedly - answering a bit blind... I'd say FLIP if you have to work on ribs & keel. My $0.02 worth; YMMV.
If you are removing the outer keel (which I highly recommend) and stripping the bottom, it is so much easier to do it with the boat upside down. Flip It!
Your back and neck and eyeballs will appreciate it!