|Sorry Mark I did not see your response, usually the site notify me when I get a message but it didn't this time!!!
The sail I have has a luff of 35.3 feet, so it will fit your boat (I,35.6). However, because the J in MK 5 (10.1) is shorter than the 11.75 in MK 3, the sail I have will be a 126%, which is some where between a # 3 (100%) and # 2 (135%).
The sail has #6 tape, made by UK, Mylar enforced with carbon tapes. The sail is generally in good condition, however, there is a small tear near the luff that I fixed with tape. The sail has a single-sided taffeta in white for added toughness. If you think the sail can be useful to you drop me a line at moefahmy at gmail dot com.
Thanks, and sorry again for the delay in responding to you.