John,

I mounted a G90 on mine, it was side mounted, there is however a nice hole for the head. I would say go for inverted mount to conceal as much of the engine and to preserve the cowling. As for the distance, no worries, the cowling is really long and you can still line it up with the back plate and not look funny. Just remember to use some light ply to reinforce the area where the screws will go into. You will need a hole at the bottom of the cowling to allow air to pass through.