According to the info I have here all the 749's have a 14T front. 13T are like hens teeth and run the chain too tight. Only real world alternative is to up the rear. 3T is a good start, and you may get away with the standard chain?
Both Renthal and STM do alloy real sprockets for them now. Rentha are about £25, the STM £58 but are real works of art
