It seems that Ultimate 40S is designed for an inverted engine so presumably the tank is set in the right position (it's worthwhile checking though). The engine doesn't care which way up it is once it's running but you have to learn a slightly different way of priming it because you're trying to get fuel to run up hill from the carb and into the engine. Also, inverted engines need a bit more care in setting the idle mix to avoid any stumbling after prolonged idling. Properly set up you don't need pumps/regulators or any other complications.