If the muffler/airframe design permits 'sidesaddle i. e. cylinder horizontal pointing to the right, is the most trouble free and safest method.

with this orientation fuel flow is never a problem, none of the flooding problems of an inverted mount or the fuel draw problems of the upright mount (some designs are impossible to get the fuel tank high enough). Also safety is improved, in the case of a conventional needle with it sticking straight up it is a far more natural position for 'tweeking' and the glow connection pointing to the right is far more conductive to safe operations than sticking straight up. The inverted mount is worst of all in this regard unless a remote connector is used and that opens the door for additional reliability problems.

John
Just what works for me