I am currently working with FPSC Classics greatest weapon smith on this very subject. Not just to bring classic weapons over, but to make them do more than they ever did before. Step one is to align the engine with legacy support, so you'll see the fruit of this early 2014 and if there is enough call for documentation I can get that started too. The good news is that BETA 1.004 has some work done on the legacy support stuff, and if you use the new weapon_legacy.fx shader, your old guns should appear in some basic form. We have decided to keep AIRMOD settings support, but we're not at 100% strength on that yet given the current intense work on performance.
Hogging the awesome since 1999