Rudin had 6 weeks of previews for Carousel and Shuffle Along. Considering Christmas/New Years is in the middle of previews and they probably wouldn't rehearse during the day that week, I don't think 2 months is out of the ordinary –– especially for a revival that is making changes to the text.
Honeymoon in Vegas had similarly long preview period (Nov 18-Jan 16), with Thanksgiving/Christmas/New Years in between.
I've never understood complaints about a lengthy preview period (as long as it's not, you know, Spider-Man-length). It's an opportunity to improve the show and make it as good as it can be when the critics come in. Sometimes with shorter preview periods, the Director is working up til the final day before Press Nights, with the cast only doing the "frozen" show 1-2 times before critics judge it. Most producers are afraid of a long preview period if they feel the show needs reviews to succeed.