It would not be flying as it should. Luff curves are specific to the flex characteristics of the spar...even within the T class sails cut for the old soft rig masts would never be used on the prebend alu masts and alu-prebend cut mains were never used on carbon prebend masts.
Plus the I20 main is a different(larger?) size then the T. If you just want to putt around the harbor...go for it but it will not perform as most would want.