RE: feul tank mounting?
"Tank paced so that the ........ in line with the carb intake orifice when plane sits horizontal." <- A Myth akin to the "fuel stays in the back of the tank" myth...
Its not really needed, else all of our engines would die in uplines and downlines... tank height predominately applies to fuel siphoning, preventing fuel from leaking out when the plane sits on the ground...
On most normal ARF's if you use the provide fuel tank position, even if you move or invert the engine, the tank height is a non-factor.