RE: Inverted OS .46 Floods
I had a plane with an upright OS20, but the tank mount was very high and I used Indy's method. I used one of those plastic fuel clips, but basically the same thing. Once I started the engine it ran fine. Also, instead of just using a "smaller" tank, you might look at a homemade tank out of something like a spice bottle. Some of those are long and skinny and will fit where a standard tank won't.