Sailboatdata sez your mainsail area is 453 sq. ft. Wind load in pounds on a sail per US Sailing is sail area times wind speed squared times .0043. If your trysail is about a third of your mainsail's area, in a 60 knot blow, the sail load would only be about 2300 pounds. So the load on a single line (and block) would be 2300 pounds, which gives you a safety factor of over two for the expected load using the 5000 pound block in a 60 knot wind. The block's load would approach SWL with a wind of about 88 knots.