I like you're idea, but there's no way I'd give up Baby for Shaq and Parker.
I definitely would. Shaq alone would be worth it IMO, and getting Parker would help fill in a void that is projected to be awful if we don't address it soon.
Consider this: This is Davis' last year on his contract. The Celtics contracts are setup so that almost all expire in the next 2 years. Davis is not a starting PF. Shaq on the other hand is a starting Center, and would fit in very well on this team. In the Cleveland series, when Shaq was used properly, he completely outplayed both Davis and Perkins. It was impressive, and that big body in the middle who can finish around the rim would open up a lot of things for Ray, etc.
If we could do it w/o trading Davis then I'd love it. But if push came to shove, I'd trade him in that deal.