Most older boats were built with a DM-2 or other stiff masts. The Dwyer DM-1 mast section has become the class racing standard for both mast and boom. New sails from the major sail makers are designed to create the fastest shapes with the bend characteristics of this mast section. It is a light and flexible mast section which is great for racing, but one which can be bent /broken in heavy air if not treated correctly (especially after rounding a windward mark and forgetting to release the boom vang.)
If you are planning on both racing and daysailing your Jet 14, you may want to keep your old mast as a daysailing or heavy air mast. Some people have even taken the older stiff masts and added trapeze rigs for “play-time”. (Trapezes are not race-legal.)
There are other articles on the Jet 14 website that address building a DM-1, Spreader rake, and rig/sail tuning.
If you choose to keep your older, stiffer mast for racing, there are suggestions by the class experts on how to optimize for racing, which starts with getting spreaders that are the same length as those in the following linked articles and locking some prebend into your mast to get the overbend wrinkles described in the cunningham section of this guide and in various sail tuning guides.