Book time is ~5 1/2 hours to ~7 1/2 hrs. for R&R of a 722.3. I'd say with post-op adjustments and "time spent", you're lookin' good at $475, especially if he impressed you with skill and knowledge already.
The Golden Rule
1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)