|Moly rings are superior in durability and longer life, although the break-in period is longer. The rule of thumb is that moly rings tend to transfer heat more efficiently away from the piston and to the block, which is always desirable.
The ring gap recommendation is set by the ring manufacturer so don't go necessarily go off the old Lotus spec. All the ring kits come with recommendations for various engine configurations: stock, track, sprint, etc. For the specific moly rings we sell in the club store (again, this may vary by manufacturer, if you don't purchase these rings- check the instructions that come with yours), for a peppy street motor, the manufacturer recommends .004" per inch of bore on top and .005" per inch of bore on the number 2 ring. Figuring an approximate 3.75 bore on this engine (they vary of course), it's safe to plan your gap in the 14-16 thou for the top and 17-19 thou on the 2nd ring.