Given the Ambassador-class was originally meant to be a prototype for the Galaxy-class, I'd say the Ambassador-class here is pretty much there: it looks like a perfect blend of the C and D, so the Galaxy-class might not look that dissimilar. Heck, it might not even come to exist in this timeline: Enterprise-D could easily get away with being an Ambassador here.
Beautiful! It looks a lot better than the original. I hope you plan to do the Enterprise D someday. I'd love to see your take on it!
Any ideas as to what an Oberth or Nova class ship would like in the Abramsverse? Personally I never really cared much for the way the Oberth looked but I've always has a thing for small ships and I'm sure you'd make it look great!. I'm guessing that the crew would still be small, about 120 or so.