Lycoming
article mainly covering the oil system changes. It mentions the requirement for fuel injection, but not where you get the fuel from. One way of solving this is to have another tank below the (upright) engine which fills up when you are upright. When you fly inverted, this tank is now above the engine, and drains by gravity feed. As these are usually quite small you are limited in the amount of time you can fly inverted, but you generally don't stay inverted long enough for it to run out.