+1 Gator or JasperI would NOT pay more for a Honda rebuild. I'd take my chances with an indy rebuild. Just recently there was a thread on here for recommended shops for tranny rebuild in CA. I am not sure how far you are from the guys who were recommended in that thread.
Personally, I would contact Gator transmission and get an authorized shop to install it in CA. Gator should come out way cheaper than the upto $4200 quote you're looking at.