I think with inverted engines you are fine on hydraulic lock if you just use an electric starter, and don't prime it first. Just let the action of the starter draw the fuel in naturally, and the engine will fire when the fuel first hits the plug. If you prime it, you're drawing a lot of fuel in there that will pool at the bottom of the cylinder, and cause hydraulic lock. I don't presently have any inverted engines (I will soon), but my dad and brother both have them, and they just use the electric starter as I have mentioned, and haven't had any problems with hydro-lock.