Have you looked at the Guest Artist agreement? If not, it's available online -
http://www.actorsequity.org/docs/rulebooks/ga_rulebook.pdfJust looking at what's online-
5. (b) On a non-performance day, rehearsal will not exceed 7 out of 8 ½ hours in Tier I, 7 out of 10 hours in Tier II, and 7 out of 12 hours in Tier III. After 5 hours of rehearsal there shall be a break of at least 1 hour.
(d) There may be one day of 10 out of 12 consecutive hours of rehearsal for each production in the 7-day period prior to the first public performance of a production.
(e) Costume and photo calls shall be included in rehearsal hours.
But, best to check with your production manager about anything the company may have negotiated that is different from that standard agreement. If you still have questions, you can always contact the AEA business rep for that contract in your area. (If you're not sure who that is, you can call AEA and tell them where you are and what contract you're on, and they can help you find the right person to talk to.)