I use the stock ones for that "sleeper-look". For a leak proof seal, set the stock gaskets onto the covers with Yamabond, Curil-T, Permatex, Gasgacinch, or other. This will allow the gasket to stay put. Between the head and gasket contacting/mating areas, use Permatex-Hylomar or a bit of grease. Hylomar will allow you to easily remove the covers when you have to adjust the valves while providing an outstanding seal.
Since I started to do this, I haven't had a leak around this area. Some people recommend silicone but I have not tried it. Either way, good luck!
